The best chokes are Skeet, improved cylinder, or modified. Shooters who are serious about their scores use a shotgun with interchangeable choke tubes. This allows changing the choke before shooting at a specific station. For example, a Skeet choke would be preferred when shooting at a running rabbit target. A jumping teal target is best approached with a modified choke.
Most field guns have a modified choke.
This is good equipment with which to start. If you really get serious, there will probably be a new gun in your future and you will better understand choke requirements. Unlike skeet, sporting clays are not broken down into gauges. Currently, all scores are treated the same whether the shooter uses a 12 gauge or a 20 gauge. Obviously, competitive shooters prefer the 12 gauge because of larger shot load.