I've owned both, I have a WR250R now and really like it. While the WR is fine on the highway if highway is more important go with the DR650. Offroad there is simply no comparison, go with the WR.
BTW, I modded my DR650 about as far as you can go without putting new forks on. Waste of money. It absolutely needs new springs and a fork brace. But new shock, emulators, pumper carb, all that was expensive and just little incremental improvements to a 350 pound mush bike. Leave it mostly stock ... and enjoy (crashing).
If I could pick up a DR650 cheap I might go the bigbore route to make the scrambler NOBODY will make. Well maybe Husky does now.
Once you get use to the WR250R powerband that feeling of "nothing low down" goes away.
2012 SYM Wolf Classic 150
2000 Sprint RS 955i (again!)