I would heartily recommend Disgaea myself. For the same reasons Montez recommends, and on the fact that you can basically play it forever. After you beat the game, you can start the storyline again with your characters and items from the previous play-through. There are eight different endings, which make this feature worthwhile; not to mention randomly generated "Item World" dungeons (
which improve the statistics of your items, not to mention garner experience). I believe it is your best choice, if that sort of gameplay appeals to you.
There are plenty of other jRPGs, besides those which have been mentioned previously, which might appeal to you; such as Steambot Chronicles or Star Ocean: Till the End of Time.
Well, a little research gives me
Deaf Gamers, which is a review website. You might want to use that website to check on the deaf aspect of the games.
A rundown on their reviews (
which don't cover the full PS2 library) reveal that Disgaea, Shin Megami Tensei: Digital Devil Saga, Final Fantasy XI (
though you have to activate subtitles in the options menu), Shin Megami Tensei: Digital Devil Saga 2, Star Ocean: Till the end of Time, Steambot Chronicles, Suikoden IV, and Suikoden V are all good for a deaf gamer, with only insignificant issues if any. Final Fantasy X is the only one with problems, even though it has text, because it is hard to read and can go by too quickly. The rest of the recommended games don't have reviews.