I had two long testrides on the Versys before buying the VStrom. There's no doubt it's a good bike, in some ways a match for the VStrom.
Engine's probably a match for the VStrom, maybe not a strong but a bit livelier and sounds good too. Gearbox not quite as good, but this may be due to the mileage of the bikes I tried.
Wind protection is better on the Versys as are the brakes. The buffeting on the VStrom can be easily fixed.
Build quality, both good but not brilliant, maybe the VStrom has the edge here.
Suspension not brilliant on either, poor front suspension on VStrom, the Versys is has a shorted wheelbase, seemed to get upset on bumpy road.
Looks again very subjective but I think the new Versys probably has the edge, the old silver framed Versys is a bit ugly.
Headlight and instruments, a clear win for the VStrom.
Potential Offroad ability again the VStrom is the winner.
Passenger carrying ability yet again the VStrom wins.
Fun factor, very evenly matched, lot of fun, both better than the Transalp.
Handling I'd say the Versys is sharper (sportier), the VStrom more relaxed (good for touring).
The clincher for me was comfort, which the Suzuki wins hands down. The Versys feels okay in the shop, but after a while on the road the odd, slightly chopperish pullback handlebars and more cramped leg position really started to bug me. Couldn't cover the rear brake on Kawasaki properly because my legs felt cramped (I'm tall) and this also affects gearchanges. The seat also tends to lock you in one position. The VStrom feels like a much bigger bike, lots of room.
I'd definately advise a long testride on the Versys if you're interested. I'm glad I took the trouble, the Versys is a great bike and my nearest Kawasaki dealer is VERY close to my house so it was tempting. But the riding position just didn't work. Like I said I tried the Transalp 700, used to have a 600 but the 700 was a bit of a letdown by modern standards. Also tried the F650GS (twin), which was the maybe the best of the bunch but just couldn't bring myself to buy a BMW in the end.