A KLR is by far the best bike for the money. The R100GS is by far one of the coolest bikes for the money.
And to really throw you off; the KLX250S is the best trail bike for the money.
Both the KLR and the GS are excellent hwy bikes and in the right hands decent trail machines too. Make no mistake both are heavy pigs.
The KLR is very cheap to acquire, and maintain. The GS not so much.
I just bought my third older KLR for a travel bike off the flea market here. They just make too much sense and they're a blast to ride.
I was also scoping out R100GS's but just too expensive to acquire and I know from experience they're also expensive to maintain.
That said many here like myself own both a KLR and a GS.