Depends on what you want the ball to do. These days, I'm only familiar with the Hammer line, so these are some suggestions:
Heavy oil conditions - Black Widow 3.0, Hammer Effect, Extreme Envy
Medium oil / starting to break down - Arctic Vibe
Light oil / lanes broken down - RAW Hammer
There are a lot of parameters on a bowling ball which affect performance, like coverstocks. Pearl coverstocks give you large amounts of length down lane, so you'll see a smoother arc. Solid coverstocks really grip the lane and react quickly to friction, so you could see more of a snap in the friction. Hybrid coverstocks are in the middle.
Honestly, I would talk with your Pro Shop, tell them what you're looking for in a ball, and let them decide which is best for you.