KLR 650 vs BMW GS
Lots of good points here. Best thing to do is try out the KLR, the BMW 650 GS single, the 650 twin, the 1200 GS, adn maybe the Suzuki Wee Strom 650. Allare good bikes (and you will find occasional clunkers in each). I have ridden all at some point. I currently own a KLR 650 2002 (bought it new in 2002), a BMW R1100RT 1996 (bought it used from a fellow BMW club member) and a Triumph Scrambler 2009. Got pretty much all of the bases covered with these 3 bikes (though I still lust after other bikes too). I have given thought to getting a Triumph 800 XC (test rode it, a very nice bike), a BMW G650 or F650 or even a BMW 1200 GS. BUT if I absolutely had to get down to just 1 bike -- and I'm not there yet ad hope not to be -- I would keep the KLR 650 for many of the reasons already cited:
1. cheaper and much easier to maintain than the others
2. lightest of the 3 -- a plus in picking up a dropped bike and in handling (although the Scrambler is a close second in handling -- the RT is fine under speed but is more of a chore in low speed handling and certainly is not the choice for any off road)
3. The seat height and seating position are great for me -- 6 foot 2, 195 lbs.
4. It is basic uncomplicated bike
Yes, of the 3 it is slower, lower top speed, vibrates and consumes oil at higher RPMs, does have the wind/weather protection of the RT, not as pretty as the RT or as classic as the Scrambler but as an all around jack of all trades master of none, it is a great bike. I've made lots of upgrades -- suspension, seat, luggage, bash plate, controls, taller windshield, moose hand guards, etc -- but that's the great thing about it -- you can do all this at once or as you get to know the bike better.
My 2 cents plus. Good luck with your choice.