You missed an option: I don't really care, as long as it's playable.
Well I think every true roguelike-player feels like that. Question is what do you -prefer- (with whatever you put behind that word, maybe a 3D-roguelike will come out that blows your mind, but until it does, perhaps you've had the best experiences with clean ol' ascii
.
To me the ascii-graphics represent imagination. That's what usually separate good/bad RPGs; if the player gets so into it that the imaginary world he/she is tumbling around in becomes a part of them. With ascii you kinda don't have any options. You have to use your imagination, if you don't, you only see a screen full of letters!
I have tremendous respect for the 'T' in Rogue
The yellow g's too early in a Crawl-game, etc.