DM must be in it for the players. My play style is gritty realism. I am for sticking to the letter of the rules, and while I love to see a lot of house rules, I prefer to see those house rules in writing before the start of the campaign, or at the beginning of a chapter if it must be done. I enjoy heavy RP and fast paced combat in equal amounts. I think the best combat scenarios are over on the surprise round. I find high damage rolls to be exciting, and think large hit point pools are obnoxious. I like my RP with plenty of skill tests and will/charisma saves. I prefer playing characters with moral freedom. I find it therapeutic to play alignments that fall somewhere on the sociopathic spectrum, and have a good track record making it work in any-aligned groups without taking things to a PvP level. (If there are any doubts, I have no problem with working an unbreakable magical oath into my backstory that would create an artificial restraint.) It wouldn't be D&D if there weren't battles against monsters and monstrous humanoids, but I also enjoy combat against human antagonists, and antagonists of the other player races.