Some general comments and even a repeat and expansion of my earlier point...
Even a "well designed" sorcerer may not have the best spell in a given situation where a specific or very narrow niche of spells will make things a whole lot easier. Specifically it is less likely he will be able to dial-up a spell answer to a "puzzle challenge" scenario.
Neither can a fighter, a rogue, probably a bard, and depending on the puzzle maybe even a cleric or a druid.
The key is the sorcerer is not a class or usually a character who INTENDS to approach these problems looking for a specific trick key that will unravel the situation entirely. His class and perhaps character approach (if character matches class choices) is to have something useful to dealing with more typical challenges and dealing with them solidly and opporessively.
The wizard on the other hand, as a class, is absolutely intended to be the "few key pieces" type of class which meets a wider batch of situqtions with a lesser number of more precisely targetted effects.
A sorcerer will typically find one or two of his spells as useful options in a given situation, assuming he has chosen a variety of spells, and will then be able to burn slot after slot of level upon level to ram those spells down the throat of the scenario until it squeals. If he knows fireball and meets a fire elemental he will throw magic missiles and endurances or maybe endure fire a lot.
The wizard would be more likely to approach the same fire elemental with protection from fire on one key fighter and perhaps a cone of cold or an appropriate fire shield or an ice burst.
These are two equally valid approaches.
It is no more reasonable to criticize the sorcerer for being less than flawless at choosing a WIZARD STYLE answer to a problem ("he cannot dial up the specific key spell like "commune with other plane" on demand") than frankly it is to criticize the wizard for his lack of slots for "hammering him down."
BTW, as an aside, the sorcerer's MORE SPELLS PER DAY is NOT just a count of available slots, but the additional fact that theslots are never wasted. he will never have a slot or two spent for a dispel magic and a silent still dispel magic go unused because his adversaries today were bruisers. Think of it this way... every sorcerer slot is a magic missile until the situation demands another spell.
a decent sorcerer (after the first few levels) will have some direct effect spells, some party assistance spells, some terrain generating spells and so on and be able to find one or two reasonable and helpful in most any challenges, with the obvious exception being puzzle challenges specifically designed to hit a blindspot of his.
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I would not prefer having a sorcerer as the SOLE spellcaster in a party of four. Without at least one spellcaster to cover demands such as dispel magic and such, the sorcer will be forced into the catch-all cover-every-possibility role that the classes such as cleric and wizard do better.
As the second caster in a party, with a cleric or a mage, he is good, though if the other is a cleric then a wizard is also good.
In a larger group, as say the third spellcaster, the sorcerer is IMO the preferable choice, especially if one of the others is a wizard. His hammering approach will serve as a great contrast to the others.
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I prefer to play the sorcerer for several reasons.
First, i find the wizard to be very much less fun to me. One reason is that he is definitely a class for bookkeepers, requiring a lot of money work with spells, scribing, and the like. Another reason is the bookish mage pouring over his spellbooks and spending a LOT of time, most of his downtime, nose deep in his scribing and arcanist stuff is BUT ONE character type. If i wanted my character's spare time to be spent 'at work" in a workaholic flurry of scribing, I would play more wizards.
The sorcerer is a basic no frills guys which means i can add to him many different "personalities" and produice very different characters to play. I have played a performer/musician as a sorcerer who viewed his spells as songs he composed and who chose most of his flexible spells as comfort spells... choosing mount because he got tired of dealing with the care and feeding of his own horse, for instance.
A sorcerer means less bookeeping, more flexible time, wider scope of character concepts available to me and the DOWNSIDE is that when i meet an unusual situation i have no direct answer for I have to try and find unusual solutions (as opposed to taking 15 minutes to dig out the key from my spellbook). I actually consider the latter issue of me being tasked now and again to find a way to make it work anyway, even if i don't have the perfect spell for the puzzle, to be a pleasant and intriguing thing.
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However, the main difference between the sorcerer and the wizard is INDEPENDENCE.
A sorcerer is pretty much well defined and understood in terms of what he can and cannot do. Under a new Gm or even a known but only moderately competent GM, I know what my sor will and wont be able to do and can plan accordingly. I am INDEPENDENT of many campaign influences and GM whims.
A wizard is HIGHLY DEPENDENT on a great many things not defined and very much subjective from campaign to campaign.
How much free time is there? How knowable is it in advance? How relaible is it? These all directly impact my wizard's ability to scribe spells into his spell book and make scrolls, much less other items.
How localized is the campaign? Will we be moving a lot or staying in an area and setting roots? These directly affect my wizard's ability to market and network for scrolls and the ability to have an arcane lab to make items at all as required from the PHB.
How PC driven is the campaign as opposed to NPC driven? Are we often taking the initiative and pursuing our own goals or are we fighting against the darkness as it swoops in to strike at us? This determines not only the time control mentioned above but also how much info we have in advance, how often we know ahead of time specific dangers and thus how good i will be at having a "key spell" prepared. A wizzard caught in an unplanned assault probably has several slots open or on non-combat spells.
How many resources for advance information exist in this campaign? is the big bad and his minions an invading neighbor who we have been fighting for hundreds of years (so that i can prepare in advance with good choices and accurate expectations) or is this some new threat long since forgotten where i will be continually meeting new and unexpected dangers (so that i will liekly be going for multipurpose spells rather than the key spell sets)?
How free is money in the campaign? IS wealth frequently tied up in found treasures which are difficult to sell for "materials" i need for scribing or for item prerequisites or is there a glowing magic commerce so that i can turn the "surplus" +1 staff we find into 1000 gp of scribing components?
Are the enemies mages more often sorcerers or wizards or clerics... or to put it bluntly, how many spellbooks will i find and capture?
Are there mage organizations, houses, or even a well organized church of boccob so that i can reliably expect to find resources other than captured scrolls and captured spellbooks for acquiring new spells?
How often are scenarios run where PCs LOSE THEIR STUFF... whether by having thing stolen, broken, specifically targetted by cunning enemies or simply having to abandon them? How often do i have to suffer the loss of one of my spellbooks?
etc...
etc...
etc...
From looking at arguments on these boards, some people think the sorcerer is a clearly preferred class... and they tend to cite many of the above issues of campaign definition as going against wizards... probably because the campaigns they have been in have seen those in play.
Some people clearly see wizards as OBVIOUSLY the superior class, and they likewise often see the above situations as playing out in the wizard's favor... they may see time as OBVIOUS...you can just take the time... or see BBS as obviously available... and consider the loss of s spellbook to be inappropriate gaming... and so on. They presume bulging spellbooks because thats what their campaigns allow.
One very basic reason i so dislike the wizard class and consider it a flawed design gamewise is that its balance is tied up so much in these "non-defined" campaign specific elements that it is impossible to assign any value to the class without knowing a whole lot about the campaign scope and story arc.
DND 3e specifically has a goal of making classes balanced, and even went to the point of defining wealth by level for campaigns because they recognized its impact. The wizard class fails to make this goal possible, without a whole lot more campaign pre-definition.
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All that said... look at my sig line.
In truth, he is what we all see.
The value of any class, or rather its characters, is set by the usefullness of its abilities in PLAy and that means it is entirely dependent on what challenges are faced.
As such, it all boils down to the GM for his campaign defines and sets what the value of each class/character is by choosing the challenges he throws at them. How often does the wizard run into a situation where his bulging spellbooks hold a key spell or how often is 10 magic missiles in a surprise engagement the answer?
So, frankly, regardless of how good or bad a job wotc does in its core rules, in YOUR GAME you the GM are the one not only responsible for making things "balanced" between the characters but you are the one and only one who has the ability to do so.
Balance defined as "IN A GENERIC CAMPAIGN" is meaningless since none of us actually runs a GENERIC CAMPAIGN.
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Long and short...
for my preference, the sorcerer provides me a wider rnage of character types that fit well within his class than the locked into the academic-bookish-study-guy wizard class does. His power is more consistent and less circumstantial in its application. His play is more a case of using his tools than selecting his toolkit with all his bookkeeping done away from the gaming table rather than during the game.
All of these lead me to prefer the sorcerer class IN PLAY to the wizard class... not because of balance becuase balance will occur or not occur between these two classes depending on the GM and his skill and savvy.
Enjoy your games.