I believe the 1 hp or 3/4 hp two-speed would be plenty, but I think it would be a good idea for you to wait for some of the more experienced members on the board to chime in.

As far as brands are concerned, I guess any of the major names are good - Pentair, Hayward, Jandy.

I am getting Pentair pumps.

If you call Pentair tech support, they will help you select a pump. I imagine that's true for any of the other companies as well.