My list:
1. Entertaining - if it's not fun, why bother?
2. Genre/setting/theme that interests me in some way. This could be something like: low fantasy, morally ambiguous game that asks the question: How far will you go to change the world?
3. Simple rules. I hate stopping game play every ten minutes to look something up. ESPECIALLY when there is no index, or the index is awful.
4. Potential for ongoing games/stories. I've played several indie games as one shots, and I enjoy them, but I prefer to have longer games that allow characters to develop over time and the potential for long stories.
5. Fun or short character creation. I hate spending an hour (or longer) on character creation that feels like work. Simply put: character creation needs to be fun or short.
6. Does not require supplement books to play. I don't mind supplement books, and often enjoy them. However, I can't stand lugging around a shelf of books unless I have a damn good reason to do so.
7. Conflict resolution that is either cinematic, simple or both. I don't mind making four dice rolls for a single turn if I get to narrate something cool, but I'd much prefer making a single (easy to figure out) roll and getting to make that same narration.
8. The game should promote roleplay. I don't care if other players aren't using funny voices (I do), but if the game doesn't get them to think about their character as a character and not a pawn to move around, then it's not really a roleplay game. - I will say sometimes this is the player's fault, no matter how good the game is.