I have no intention of spending 30+ pages and countless hours debating every class ever published. You can go get out your splatbooks and see if you can't apply my arguements to them yourself. The arguements against the power level of a great many classes, are against the lack of specific flavor of many others are well known and are not spoken of only by me, but by a great many reviewers. I am though among the most vocal opponents of classes like Acrobat, Duelist, Cavalier, and others that are simply collections of class abilities that would work well as feats, but please don't try to tell me that this is the first time you've heard anyone criticize PrC's. So, yes, take away all the PrC's I consider poorly designed and overpowered and you aren't going to be left with many.
I can talk about a few cases, but you are probably better going at reading smetzger's poll threads to see how many agree that there just isn't a significant down side to many of the PrC's - even the DMG ones that most consider some of the best examples of good PrC's.
Do not assume I misunderstood Ranger. I understood what he meant perfectly. Let me reiterate. While in theory a fighter is a generalist in combat, we all know that in practice fighters are specialized to perform certain tasks. One may be a two-handed weapon basher, another a defensive expert, another a two hand fighting style crit specialist, another a mounted combat expert, another a spiked chain expert, another a shield bash expert, and yet another an archer. While thier may be a few fighters out there who split thier bonus feats evenly among melee, missile, and mounted so as to be good in every field, I seriously doubt it. Such fighters would be 'sub-optimal' in the parlance of character design. So, it is pointless to compare an archery PrC versus a hypothetical non-specialized fighter. Fighters are specialists. What one must compare a archery PrC versus is a fighter specialized with the bow. When one does this one finds one of two things. Either the skilled min/maxer can take a few levels in the PrC to clearly gain an advantage in archery compared to even the most specialized fighter archer, or he can't. In the published cases, he most certainly can, and they do. An archery PrC must not only be better than a fighter in archery, it must be better than a fighter can be in archery. And that is plainly bad design. It should be clear immediately that a fighter who was already going to specialize in archery gives up nothing to be more specialized and effective as an archer. Given the fact that archery is already an incredibly powerful and effective way to specialize a fighter, one has got to ask 'Why is there a need for an archery PrC?' And the answer is as I said.
As for kits, did I not say that there were cases where the concept was abused?
I don't have the quote with me, but I'm pretty sure Monte Cook has come out and said that Prestige Classes were created to be slightly more powerful than core classes.
Yes, I agree that there might be some advantage making multi-class spell casting combos more playable, but I don't feel that is a particularly strong arguement for what is at hand. It certainly doesn't justify the bulk of the PrC's out there.
One question you might ask is how much you could take away from a class and still have players take it. That in itself is not an arguement against a class, for you could still take things from cleric or rogue or fighter and have them remain viable classes - but in the context of a class being chosen in preference of some other core class it is telling.
And I must also say that my main complaints against PrC's in terms of power come in two forms. Full spell progression PrC's that also offer more feat equivalent class abilities than a Wizard, and full BAB progression PrC's that also offer the equivalent of more than one feat every two levels OR are highly fronted ended at level 1. I have much less complaint in terms of power against the rest, and admit my dislike of the rest may simply be by way of association. I wonder though how often the other types are in practice taken.
As for your specific cases, they are as I said being discussed in smetzger's threads. The DMG PrC's are probably the best of the bunch.
AA: Only the arcane requirements are burdensome to get into this class, and they are minimal. Only a single level is needed. In exchange for the loss of on average 3 h.p. and +1 BAB, the character gains the ability to use wands, +2 to will saves, assorted minor abilities (familiar, scribe scroll), and can select a variaty of buff spells (true strike) which will complement his style. In the context of a missile fighter, this is almost a wash. The class itself exchanges 5 bonus feats and 10 hitpoints for good reflex saves, a much better skill list featuring spot and listen, a couple of minor abilities of increasing power, and the incredibly powerful ability to elimenate the bows biggest drawback - its reliance especially at high levels on magic ammunition. Like I said, the DMG is probably the best of them, this would be almost a wash except for two points. First, the class screams front ended. Most AA's probably only take one level in the class for enchant arrow alone, and consider the net bonus to reflex and fort saves, and the improved spot and list a bonus. So almost noone is really giving up 5 bonus feats. Calling it one would be pushing it. Simply reversing the order of progression would just about fix the class in my mind - that is to say enchant arrow on the even levels and the extra abilities on the odd levels. Almost. The other problem is more basic and harder to solve. Given the potency of archers, is it really a good idea to offer them ways of getting around thier few problems?
But this is the least broken archery PrC. Would you want to defend OotBI, Peerless Archer, or Deepwoods Archer? How about a couple levels of each? In that context, does having more restrictions on multiclassing sound like such a bad idea? Heck, if anything, they have it backwards. It would be better to be allowed to freely multiclass core classes than PrC's. Flavorwise, if these are organizations, how many do you really have time to be a part of?
Loremaster: All of this is debated in greater detail in smetzger's thread. For a sorcerer, the requirements are a nuisance but it hardly matters for this is a Wizard class through and through. That is sort of my point. This is just a wizard - only better. For a wizard, the requirements are trivial. The only requirement on the list that is really bothersome is the requirement to take skill focus (knowledge), which really is a waste of a feat. But, does the class pay you back. Hmmm.
Well, the class gains FOUR bonus feats (called secrets)in return. Even for a wizard, this is a net gain of feats even without counting the other abilities. One gives you the feat of your choosing, so the cost of skill focus is in the long run mute. You get the feat you spent back. Another is a flat +1 bonus to your AC. Another is a flat +1 bonus to all attacks (better than point blank shot for a wizards purposes). One gives an extra 2nd level spell slot per day. Plus you get the skill points you spent back with improved skill points per level, and this is probably a net gain because at the least Knowledge (Arcane) is useful and probably would have been taken anyway. Plus you gain 'Identify' at will as an extraordinary ability (no material cost), and 'Analyze Dweomer' once per day as an extraordinary ability (no material cost), and a handful of minor abilities. I call that no significant disadvantage and so I might add do many others. And again, you can front end it, taking what you need and leaving the rest. No multiclassing penalty involved.
And Loremaster is not nearly the most powerful full spell progression PrC. I would not be the first one to say that a wizard or sorcerer quickly reaches the point where there is never a real need to take another level in his class again. Mage of the Arcane Order anyone? Archmage???
Dwarven Defender: You fail to mention the classes AC bonus (itself worth a feat or more), superior will saves (itself worth much more than a feat to the usually vunerable fighter), increase in HD, the fact that the classes DR progression exceeds barbarian (how many feats would you give up for DR -/6?), uncanny dodge ability on par with the barbarian (how many feats is uncanny dodge worth?), and that while defensive stance is more limited than rage it also doesn't cause an AC penalty and can be done in heavy armor. But of the classes in question, this is the one that comes closest to being on the mark for me. For one thing, it isn't all that front ended. People taking the class are in it for the long haul probably. However, my objection to it is not so much its raw power, but that it highly overlaps Barbarian to the point of being almost a 'lawful' barbarian. After being forced once during a conversion of 1st edition material to create a PrC for a lawful barbarian, I realized that the basic problem was that the Barbarian was a flawed core class with too little flexibility and too much flavor. People who rely on intense emotion to gain mastery in combat are not limited to wilderness born illiterate raging beserkers, but there are fanatics of every sort - religious, nationalist, pyschopaths, and so on. If PrC's are defined by thier narrowness, Barbarian is a PrC. Like Acrobat, Duelist, and Cavalier, what we have with DD is a class covering up for the weakness in the core rules. There is no reason that we shouldn't be able to construct any of them from well constructed core classes with broadly available feats and achieve essentially the same things.