I generally prefer literate. If I'm out-of-character I may use symbols to represent my randomness, especially in-game, but if I'm roleplaying I stick to literacy. I used to be illiterate a good long time ago, but now that I've roleplayed using literacy it's too hard to get rid of the urge to use paragraphs and complete sentences xD
It irks me sometimes when I see loads of incorrect grammar and punctuation-- typos I don't mind, but constant illiteracy and text-talk just gets on my nerves a bit. I use an HP laptop that lags the in-game chatbox, and sometimes it's hard for me to type without misspelling things, but I usually only get online to goof off and explore, though I enjoy a roleplay or two once and a while. c: