I've watched all the modern stuff, but my lack of classic Who knowledge means I don't think I have enough info to vote. I like all the Doctor's I've seen, and honestly its hard to pick between 4, 9 and 10. I also like 11, although maybe a little bit less than than 4, 9 and 10. I thought 8 was good in the move (even if the movie itself was weak). I've also watched The Three Doctors and the Five Doctors, and I liked 1, 2, 3 and 5 in those specials (especially Troughton, he's definately the classic Doctor I want to check out the most after the 4th, who I'm watching right now). The War Doctor was also really good in Day of the Doctor. I've only seen 7 in the movie, and I've seen nothing of 6, but I'm sure I'd like them, too.
That said, if forced to vote, I'd only feel comfortable choosing between 8-11, which I've seen every thing from (not counting 8's audio adventures, but you don't "see" those anyway). So, from that group, If I had to choose, I think I'd have to go with 10. He had my favorite episodes, favorite farewell, and was just overall an awesome Doctor. 9 might have beaten him if he'd had more time, but right now I'd say 10 is probably my favorite Doctor, with 9 and 4 very close. I'm not going to vote, but that's who I'd choose if I had too.