I own a XJ750 which is a smaller siced XS1100 in a way, it has shaftdrive. I like the shaftdrive, because it's less maintenance and I can still pop wheelies on it. But the chain drive is honestly the way to go.
There is a lot more available for the XS650's lots of parts etc. The xs1100 is a horse, and also heavier. It depends on your size as well. The XS650's are a lot smaller and can be manhandled very easily. I have a 73.
The 850 is a triple right? Stay away from those.