I had an '08 250XCF-W and found it challenging to ride in tight technical stuff as the motor really needs to rev to generate power. I ultimately had it bored to a 320cc. I suspect the owner of the bike you are looking at probably had the same issue.
The WR has a much wider and friendly powerband. The KTM has better suspension.
Both will do the job but the WR is easier to ride.
My .02 cents.
(Before this gets punted to thumpers.