It all depends on what kind of sail you're going to use. Symmetrical or asymmetrical. A bowsprit is useful for attaching the tack of an asymmetrical spinnaker. You don't need a pole with an asymmetrical chute.
If you're running a symmetrical chute, the pole length is normally the same as your J measurement (distance from the front of the mast to the tack fitting on the bow). The Bavaria 50 Cruiser has a J of just over 20'. That's a pretty big pole. Not sure what the Vision J measurement is.
Some racing rules limit pole length or penalize you for a longer pole. For cruising, a longer pole with a symmetrical sail can help with speed, but frankly I wouldn't want to go cruising and have to gybe a 20' spinnaker pole!
Whisker poles are only used to pole out headsails. They don't work well with spinnakers, which apply far to much compression to the pole.
I have an asymmetrical sail on my Bav 44. I keep it in a sock and can launch and retrieve it by myself.
Jake