MacDive is the best if you are a combined Mac and iOS user. It’s a bit annoying/unfortunate you have to buy both versions separately buts it’s by far and away my favorite. The developer is really responsive on his site too.
SubSurface is the runner up. It’s free and works on any platform under the sun. I really dislike it’s interface however.
SubSurface is the runner up. It’s free and works on any platform under the sun. I really dislike it’s interface however.