I had a KLR650 for 8000 miles and am RTWing on an XR650L.
the KLR was my first thumper and I was pleased by the comfort, power and off-roading. maintenance was a bit of a pain, but OK if you can find a friendly workshop who'll rent you some space to do stuff yourself. much is said about the front fork, but its no better or worse than the XRL.
the XRL needs a lot of work to make it comparable. I fitted a 43 litre tank, but that meant welding mounts and shortening the seat. the tank's great, but the seat is the worst I've ever used! you could go for the 22litre tank, but the KLR will give you more power and way better fuel consumption (20-30% better). off-road, the KLR will cope with what most people go for, but the XRL is more capable on jumps. if you're going to ride gravel roads and mud, the KLR will be fine.
so why'd I buy the XRL? simply cos I fancied a "project" and I could fit a 40+ litre tank, kickstart ... also, it looks terrible so no one is going to steal it ;-)
out of the crate, go for the KLR. if you're going to push the bike off road, the Adventure is better and the XR650R is better still, but needs a big tank.