My feelings on these new core classes vary quite a bit depending on the class in question, but I prefer core classes to PrCs. I think PrCs should be linked to the specific setting in a very specific manner and shouldn't just be a "weapon/spell master of X".
Classes from Arcana Evolved: I love all of these more than any of those in the PH and would happily play any of them over anything else.
Iron Lore: I can't wait to see these classes!
Other classes by Malhavoc: The sorcerer in Eldritch Might is better than the core one I think, but it doen't impress me terribly. The new bard in Eldritch Might is very cool and original though. The new classes from Roguish Luck are neat, but I wonder about the balance of some of the mechanics. The bandit is a nicely flavorful class, but I wonder at it's necessity. The Gutter Mage is neat, but I think that in a perfect world it and the Spellthief from Complete Adventurer should have been combined to make a much better executed class for the concept of the roguish-mage. The Shadowsworn looks cool and sinister, but it doesn't do a whole lot for me.
Classes published by Green Ronin: Most of these I could leave. The ones I really like though are the Psychic, Thanemage, and I think the ones in Testament are really nice for that setting, but not any other setting I can think of. I have yet to see the Avatar, but I have just ordered that book. I need to read more about others to understand them better, like those in the Advanced Players Manual. Others I am far less enamored with - the witch, noble, and others.
Dawnforge: These classes look pretty nice for the setting, especially the Spirit Adept, but I am not sure how well suited they would be for another campaign setting due to their unique take on the origins of magic in that setting - especially the disciple and shaper. I suppose the shaman and spirit adept would adapt relatively well though.
Midnight: I don't know much about these classes, but I don't think they would adapt well to other settings from what little I do know.
Complete series of books: The Samurai is a travesty of the flavor a samurai should invoke in an oriental game IMHO. The Hexblade is an awesome combination of fighter and wizard with a neat flavor to them. The Swashbuckler doesn't do much of anything for me; mostly because the Unfettered does the same role, only ten times better. The Spirit Shaman is nice and unique in the role it fills compared to other divine casters. The Shugenja is kind of neat, but doesn't do much for me - I probably only like it as little as I do because of it's ties to L5R. The Favored Soul is another class I could leave at the bottom of the barrel. The Warlock is a fantastic piece of original design and fulfills the role of sorcerer better than the sorcerer IMHO. The War Mage comes at the warrior-mage concept from a slightly different angle, which makes it kind of neat. The Wu Jen is okay, but what impresses me about them is their nice spell list - very flavorful spells there. The ninja is okay mechanically, but is nothing like any ninja I have ever seen on screen, heard of, or researched - so it gets a "no" vote from me as far as being a "ninja". The spellthief is really neat in concept, but lacks in execution I think. The Scout is simply awesome, though it steps on the rangers toes a bit much I think.
Miniatures Handbook: I have already covered the favored soul and war mage above, but the Marshal is a very neat idea with a very balanced execution - nicely done, but I don't know anyone who would ever play one. The healer appears okay too, but again the same problem - I don't know anyone who would ever play one.
Oriental Adventures: The sohei is favorite of mine, especially after the 3.5 update done in Dragon magazine. The original Samurai done in this book is by far better than the one made in the Complete Warrior. The Wu Jen and Shugenja I have already mentioned above. The Shaman was nice, but not very original.
Rokugan: The Samurai in this book is the best of the lot I think with his ability to advance the abilities of his weapons through experience or gold. The Shugenja I have already covered. The ninja here was okay, but unbalanced and still not what I look for in a ninja as far as the flavor goes. The Inkyo was very original and nice, but could have been done better I think. The Courtier is very cool and original, but I question the balance of it's mechanics sometimes.
Swashbuckling Adventures: Many of these classes are pretty neat; the courtier (same as in Rokugan), assassin, inquisitor, alchemist, witch, musketeer, noble, spy, swashbuckler, pirate all filled a role for that setting type and some I find to be really cool like the highwayman and wanderer.
Quintessential Series: I didn't like any of these except for maybe the Chaos Mage. The Samurai and Witch lacked something...
Dragon magazine: I can only think of two at the moment - a psionic class I forget the name of (and it didn't impress me, though I believe it did have a unique take on the new psionic system from the XPH, which I applaud). I actually liked the attempt to make an updated Sha'ir class and enjoyed that one, if for nothing more than nostalgia.
Eberron: The Artificer is quite well done and original.
Expanded Psionics Handbook: Finally psionics classes done right. I liked all of these classes - the Psion, Psychic Warrior, Soulknife, and Wilder. Surprisingly, my favorite of this bunch is the one who had the least to do with psionics, the Soulknife.