I have not had to make this decision as I have no money for new wheels, but I do keep oscillating between 15" or 17". I suppose there is probably a 16" wheel out there somewhere that I would like, but I just haven't found it yet. I'll probably end up going with the 15" Konig Lightspeeds, though. Cheaper wheels, cheaper tires, and probably smarter in the long run. Just really hard not to like the big wheel look.
I think that 16's would look the best, but where aren't many good tires for 16s.