Help deciding between Canon and Nikon

Hello, I got my first DSLR in December, a canon t3i and also got a canon 50d. I've decided to sell these and get a better camera, but I can't decide which to get or even which brand. I'm selling off my lenses with the cameras(i don't have any valuable ones), so I will be basically starting from scratch either way.

I'm not sure really what I want to shoot but the type of photography. I cant really travel to exotic places to take landscapes. I do like shooting wildlife and I do like shooting action, especially motorcycle races

I am looking for a camera around the $2000 range or less. It seems I have alot of choices in the used market

canon:

First I consider the 5d mk II. This is appealing because it is full frame, high resolution and has video. The downsides are poor build quality, bad autofocus, and slow fps

second is the Canon 7d. this has video and high fps as well as better autofocus. It is also cheaper. this looks like a good buy, especially for action shots

nikon

3d now under 2k used. High fps, no video, low resolution. however good build quality
d700 don't know much about this one.

I would say that I would prefer a full frame over a crop sensor.

How do Nikon and Canon compare for lenses?

Can anyone give some advice?