best folding prop?
You may discover a three blade folding prop to be a hard-to-find item! However, fortunately there are a number of excellent three blade feathering props, and perhaps one of them will work for you.
We a MaxProp which has worked well for us - I consider them the most established feathering prop - you can call PYI for fit info (http://www.pyiinc.com/). Autoprop is another popular alternative. Feathering props are more expensive than folding props so raise your card credit limit before ordering.
If your boat has a two blade as standard equipment, you may not need or want a three blade - again, get advice from someone like PYI on your specific application.