I have two males with no problems. Ben is actually Rocky's father, not that he seemed to ever know that. Funny how dogs are -- the sire seems to end his "fatherhood" at the "making" stage. But I don't think two males usually have a problem, unless they are going for the same female in heat.
But since your boy is neutered, then a female would be fine too. It just depends on what YOU want. Maybe go look at a litter from the breeder you choose and let the puppies decide for you
