I havent actually been ignoring this thread, I just didnt want to post replies that would get wiped in the server changeover.
True. But "considerably greater" is a subjective term that is only meaningful when measured at the gaming table.
I disagree, to a point. Game balance can and must be at least partially determined from the base material. Each campaign is going to have eccentricties that theres no telling how they will react with the rules, but the rules themselves must be balanced with themselves, on a certain baseline. I think the Cleric, and to a lesser extent the Druid, are out of balance with the other classes, in terms of the rules.
Defensive abilities generally do not gain a PC much glory unless you habitually play in very dangerous, PC killing combats. Where is the glamor in standing around waiting to not be killed by the enemy?
Good offensive abilities are the ones that have the sex appeal. When you can quickly take an opponent(s) out of the combat completely, that is when you can singlehandedly shift the tide of battle. Real world experience tells me that players have a lot of fun with their Fighters, Barbarians, and Wizards, even if these same PCs tend to get killed more often
Therein lies the problem with the Cleric (and to a somewhat lesser extent, the Druid). It has both. The best defenses in the game (Good hit points, full blown armor with AC buffs if needed, Good Fortitude saves, even better Will saves, coupled with spells like Death Ward, Freedom of Movement, Spell Resistance, Protection from Energy etc), combined with a full offensive arsenal especially at mid and high levels, but even before then especially if you count "passive offense" spells that hinder or remove an enemy without killing them (Hold Person, Blindness/Deafness, Command and Greater Command, Spiritual Weapon, Silence, The Inflict spells, Searing Light, Flame Strike, Slay Living, Harm, Blasphemy etc, Destruction, Fire Storm, Energy Drain, Implosion). And then theres the offense-by-enhancement of spells like Divine Favor, Divine Power, Righteous Might, etc etc.
And then of course theres the stuff from Domains. A Cleric can gain access to many of the (supposedly) superior wizard attacks and utilities this way: The Power Word spells, Wail of the Banshee, Disintegrate, Chain Lightning, Bigby's Hand Spells, Horrid Wilting, Cone of Cold, Dimension Door, Teleport, Greater Teleport, Invisibility.
Now yes, the Cleric only gets 2 Domains. But thats liable to be enough to augment their already powerful spell list considerably.
As far as who is most powerful, as always, alot depends on the GM. The GM essentially dictates which classes/abilities will be useful and which won't. If the GM runs prepared modules/campaigns, I feel they owe it to the players to let them know what won't be useful. On they player's end, they need to not make a character so specialized/esoteric/inappropriate that the GM would have to bend over backwards while baking a cake from scratch to find a way for them to shine.
Again, this is largely spoiled if the basic core rules themselves contain large imbalances. If one or two classes are stronger than all the others (and especially if a couple of classes are also somewhat weaker than the majority, or than other classes of their type) the DM is forced to spend time and energy compensating for this. That shouldnt be neccesary.
But, when the PCs have the drop on their opponents, and a round or two to set up, it makes the cleric a combat monster.
All it takes is one round for Divine Power to let the Cleric match the Fighter for any given important battle. And he has the advantage of being able to chose to forgo a round of that combat ability to cast one of his other spells as well...be it a Cure to save the Fighter (or himself) from dying, or a Slay Living to wipe out the primary enemy..
And like Ridley said, both classes tend to play supporting roles. The guy from "Order of the Stick" once drew his Cleric as a walking box of bandaids, and the Cleric can feel like that a lot of the time. If you did nothing but walk around and heal, would that be a fun game?
Thing is, nothing actually compels the Cleric to do nothing but walk around and heal. In fact, once combat has begun, healing with Cure spells especially is less effcient than taking offensive action (which the Cleric is quite capable of) because all your really doing is trading actions with the enemy. The exception to this is of course if someone is actually about to die. But generally, rather than having the fighter beat on something while the Cleric stands back and heals, it would be more advantages for the Cleric to take a round and cast Divine Power and join him, or to use Slay Living, or Destruction, or Hold Person or the like.
I think the Cleric/Druid problem stems from the fact that it was decided that every party must have a super-healer, but the Cleric in particular was an unpopular class. So the figured super it up into a mega-class would make it more atractive. But I personally think its lack of popularity is due to theme/RP/archtype issues. Most people choose their class based on taste and theme, and then maybe try to construct it so as to make it a strong character. But I just dont think the archtype of the Cleric appeals to a lot of people. The Druid seems to have less of these issues (which might be why its not nearly as over-strenghthened)