Everything I've heard about the G29 is that it's a solid wheel. I had its little brother, the Driving Force GT, for quite a long time and it served me very well.
I have moved to a T300 RS GT, which I was able to pick up on sale for $299 a while back and I really, really like it. That said, I am 100% certain that I would also have really, really liked the G29 if I'd bought that instead.
There are some issues at present with the T300, though I've found it acceptable with the latest firmware and the fan switched to always on mode. Unlike some, with these settings and the force feedback set to 1/1 I do not feel as though I'm in danger of breaking or damaging the wheel, but it's possible that you might want to wait until the T300 issue with GTS had been patched if you go that route.
I rolled the dice on the T300 given the reliability reports and I'm very happy with it so far. A few months from now, I might not be, but I really like it so far.
Honestly though, I think either wheel will make you happy as long as you have a solid base for it. A good wheel stand or something like a Playseat Challenge is a lot better than strapping the wheel to a desk or coffee table.