Depending on your wishes you might pick a soft or harder, small or bigger wheel.
Skateboard wheels with a durometer of 95A to 99A perform well on almost any surface, and with a 53 to 56mm diameter they will get you going in the skatepark and at most street spots.
Skating transitions is very dependent on the surface of the ramps. For smooth concrete as in most bowls, hard wheels work very well. On wooden ramps a little more grip can be pleasant, so medium-hard wheels are recommended. The diameter should be at least 56mm to keep the speed.