I have owned both the BMW f650GS twin and the Tiger 800 Roadie,
The Triumph is far superior in my book if most of your riding is on the pavement. Turbine smooth, much better response and very broad power band. Only thing you need is a windshield from Madstad and luggage to make it a great touring bike. Downsides are that the engine has a whine and there is a bit of a heat problem in warm weather.
The Beemer is a good bike but always seems to be working too hard after 65 mph (buzzy) and doesn't feel as stable at speed as the Tiger. Also the BMW seat feels like a vinyl covered 2x6 after half an hour so there goes another $500 in addition to a decent windshield.
I traded the T800 for the Explorer. Very powerful, very good on the highway but heavy when not rolling. I love it but kind of miss the ligher T800