I had an old KLR and loved it. If you buy them used they don't lose much value. It will cost half as much to buy as a BMW, parts and farkles are everywhere for cheap and on the rare occasion that something breaks you can fix it with a zip tie and some duct tape. Never had a problem with mine, and it was beat to shit when I got it.
OTOH...if most of your riding will be on the freeway, the KLR probably isn't for you. It's happy at 60-70 mph but above that it's a vibrating, oil consuming unhappy camper. "Smooth" is not a term that will ever describe a KLR. As my riding took me further from home and required more slab to get to cool stuff, I realized I needed something different. Hence, the Wee Strom now in my garage.
The BMW is a nicer machine, but that comes with a higher purchase price and higher maintenance.
'08 Triumph Bonneville T100, '04 Suzuki DL650 'Strom