Id been considering GT/ Marin bikes but Kona look really good too, off to the classifieds
Beware buying a specific size, from experience GT and Marin come up a lot bigger than a Kona
I could probably get away with riding a 19in Kona, but would have no chance with that size in a Marin
You need either the c to top or c to c size and even then they won't be exactly the same
If you are not used to it alu can feel very harsh, but used to prefer the more direct ride (not sure my old body would these days)
Something like a steel Stumpjumper would be nice or if you can find one a Breezer, loved mine and wish I still had it
Maybe even one of the cheaper Ti frames such as an Airborne or one of the other non boutique brands, strong, light and less prone to corrosion