The G3 is one of the best gun for gp only. It has scored 10/10 in a fewyoutube videos.
If you are buying a perm G36 VALKYRIE, dont bother, just use the gp one; they are the same. Also to decrease recoil add a supressor, they work like a gem. You will however often be called a g36 nub
NOTE: You can't attach a scope to G36, it has a built in one (which is like a snipers)