I'm sticking with 3.5.
I'm mixed on what I've heard about 4e, but the bottom line for me is this: if it ain't broke, don't fix it.
I like 3.5. I've just picked up a ton of cheap and very good 3.5 books that won't have 4e equivalents for years. 3.5 fixed a lot of what was bad about 3.0. I'm familiar with 3.5, I've got a lengthy and useful set of houserules for 3.5, all of which I'd have to start over again if I switched.
Even if 4e was better, which I'm not sold on, I'd rather run 3.5 well than start over and fumble around with a whole new set of rules.