Favourite RPG? I'll be the deviant here and go some place completely random:
The WayIt's not completed yet (only 5 episodes released, out of an unknown amount), and it's 8-bit, made with the old RPGMaker2000, but heck, it's got one of the best storylines I've ever seen, a good custom battle system along with the default one in Rm2k, and hey, it's free. Very well done, and the fact that the game is made mostly by one person is truly amazing. And like I mentioned before, one of the best storylines ever. I haven't seen such a unique and intriguing storyline before. If you have the time, I'd suggest you try it out.