I've ridden the Transalp, Vstrom and F650GS (800 twin). Very difficult to choose between them, but I'll probably end up going for the Vstrom which is certainly better than Transalp in virtually every aspect except offroad ability and build quality. It was a lot closer with the BMW, which felt a like a lighter version of the Vstrom with sharper handling. I won't be going for the BMW, simply because it's a bit pricey and am not happy buying a bike in the first year of production. But it's fractionally better than the Vstrom in many aspects, but not enough to justify the extra money. But the Suzuki is noticeably more comfortable than both of them. All bikes are very easy to ride onroad.
As for the F800GS, I suspect this is in a different league, in terms of outright performance and offroad ability. But it is expensive.