Some praise for Aprilia
Can't really help on your choice, bar the fact I've had my 1150 non ADV for about 6 weeks and put a thousand miles on it and love it, the handling is so much better than you'd think, looking at it. Before this I had a Tuono for 2 years and a Falco for 2 years before that. Both my Aprilias never missed a beat, had better than Honda build quality and were fantastic. I sold the Tuono as I wanted to slow things down a bit after a friend got badly hurt, not because of any faults with the bike. Sorry, just wanted to show the other side of the Aprilia coin.
One thing I did find with the GS is that it took a fair few miles to adjust to it, and I did think I'd made a mistake at first, but once you're used to it it's great (probably don't need to say that on this forum!). Build quality seems a lot lower than Aprilia though, at least they've always used s/s fasteners!