IMHO, the best PH is what your tap water is......
and mine is 8.0-8.2!
Unless your trying to breed certain fish, then, and only then, would I play with it, and that would be by lowering/raising the KH by using RO(to lower), or buffers(to raise).
As far as temp., depends on the fish. One tank is at 74, one is at 80, and one is at 76.