I have a
BU-353 and it has worked well for me. It seems like it takes a long time to get a lock from a cold start, but I don't have anything to compare it with except my Magellan handheld.
My personal feeling is that any mainstream GPS receiver out there will get the job done. You could spend some time comparing specs, but I doubt that any differences in specs would be noticable while you're motoring down the road.