Welcome to the HUBB !

We have incredibly similar tastes in bikes I actually own both models in your question so here comes one of those rare occasions where I feel like I am maybe in a position to add to the discussion.

The short answer is : no contest, go for the W800.

The long version : they're both very good bikes. The F700 is easy to ride, with a peppy twin engine and has that GS family look about it that sits well in the current fashion fad of adventure biking. It is however really just a friendly upright road touring bike with very modest off-road abilities and that's what I bought it for (about 18 months ago). On a ride out with some friends in March, I ended up at a Kawasaki/Yamaha dealer who had a beautiful 2013 red/black W800 special edition demo with a good price and I just had to have it. Justified it to myself by saying they were very different bikes fulfilling very different "needs". In reality, the W800 does pretty much everything the F700 does (in a bit more "tuned for torque" kind of way). I absolutely love it and have taken it to all kinds of places since I bought it (including the fantastic HUBB UK weekend). It works very well in every environment (city, motorway, countryside) and works just as well for light off-road as the GS does (I have actually done this more on the W800 than on the F700). Some soft bags strapped to that very comfy seat and you're good to go.

To your specific questions: yes, the BMW has abs and better brakes, better suspension and more HP. A Bonneville also has more HP and better brakes (had one for a few years) but like Andy says "includes parts made of cheese".

My conclusion here : the W800 does pretty much what the F700 does but gives me much more joy/happiness. Nothing rational about, it just does !