The question is based on logic, and Greg K's response is a seemingly plausuble logical response. However, I don't buy it for a minute.
You would be wrong. If you have been around here longer, you would know from various threads over the years that I believe no gaming is better than bad gaming. You would also know that I am very selective about the games in which I will play.
1. The DM needs to have done work on the setting and set its races, its cultures, its deities (and tailored their domains and spell lists), established house rules etc. before the game starts
2. No kitchen sink games, no Ebberon, no Planescape, no Spelljamer, no evil campaigns for starters
3. No games above level 10-12
4. No powergamers or butt kickers (by this this, I mean rate mid to high on a scale of 1-100 respectively) or the DM must be capable of reining them in
5. No char ops, min/maxers or rules rapists. The DM needs to be willing to put RAI and the good of the campaign as a whole above abuses
6. Limited use of WOTC players supplements (with the DM tailoring any available PrC choices to the campaign) and no XPH, Bo9s, ToM, MoI. I will go for some Unearthed Arcana options. I will go for the use of Green Ronin Master Class books and some other third party material (This is mostly, because I don't think highly of most WOTC player oriented material or alternative mechanics in general)
7. Few if any dungeon crawls
8. Must be a long term campaign. No one shots
9. Must be sandbox that allows the party to go off and follow their own pursuits
10. If something RAW is disrupting the game, the DM needs to be willing to take control and change it or set limits
and, if there are any doubts, I just turned down a game run by one of my friends for violating 2,3,5, 6 and 10. 5, in this case, just happens to be another friend whom will powergame and attempt to Char Op under this DM just to annoy him and see what he can get away with (and much of his char op attempt is not understanding the rules, stretching the rules and the DM not knowing better or caring to stop it).
Edit: As for my favorite classes they include the following;
WOTC
1. Rogue
2. Rogue w/ the Martial Rogue variant (Unearthed Arcana)
3. Rogue w/ the Wilderness and Martial Rogue variants (Unearthed Arcana)
4. Ranger w/ the Complete Champion spellless variant
5. Barbarian w/ the Hunter variant and Favored Environment variants (Unearthed Arcana)
6. Fighter
7. Sorcerer
8. Cleric: using the cloistered cleric variant (as a start to make less martial) and spontaneous divine casting variants (Unearthed arcana). Plus I am willing to limit my spell choices further based on my deity's list of domains and a handful of other spells (e.g., augury, bless, remove curse). Why? Because I am fan of 2e's Specialty Priests and think Clerics should have been more specialized in spell choices and some class features to reflect the deity.
9. Oriental Adventure's Shaman (tailored to be a divine caster)
Non WOTC
1. Green Ronin's Psychic
2. Green Ronin's Shaman
3. Green Ronin's Witch
4. Hong's Knight ( a tailored OA Samurai) combined with the options from Green Ronin's Caviler's Handbook
Which class I will choose depends upon the campaign, its culture and both my character concept and mood.