I don't believe that the young man was asking about what larger pythone species is good for a beginner herper, but what species is best for a first time keeper of the larger pythons. The OP has extensive experience with snakes and other herps, but not giant pythons.

I am of no help brother, I would say to go with what your heart most desires! I have no desire to get a retic but would love a burm or an olive python. Whatever you do, post some pictures, otherwise it didn't happen!