Choosing a bowling ball depnds on whether you are a casual, once in a while bowler or bowl regularly in a league or tournaments.
The surface material of the ball is probably the most critical aspect to consider in purchasing a bowling ball. This determines the friction on the lane as the ball travels down the lane. More friction gives more hook.
Following are the different types:
Polyurethane or plastic--Great for beginners. Has the least friction. Fairly inexpensive and easy to control.
Urethane--Gives better pin action than plastic and has more hook.
Reactive--Called this since the ball reacts to the lane surfact. Good pin action and hook.
Particle--Designed for maximum friction and maximum reaction to the oil on the lanes. Good for bowling with a high speed ball. This ball has minute particles added to the surface which has a grabbing effect on the lanes.
Whatever type of bowler you are, having the right ball is very important.