I do not own but have ridden a f650 once and I wasn't that impressed, felt like a heavier version of my XR650 with a little more comfort but a larger price tag. I do however own both a Wee and a Tiger but have not had the Wee off road yet. The Tiger feels very stable on the mild fire road but I think the Wee would probably be a little easier off road due to the lighter weight. As for power the Wee is impressive (i also have the smaller 885 Tiger) but does not feel as smooth as the Tiger. As for comfort the Tiger wins hands down, but for fuel mileage Vstrom takes it, but the overall fit and finish with the Tiger is better. All in all I would go with the Tiger.
That didn't help one damm bit did it?