Why the question ninja? (o゚▽゚)o
(≧∇≦)/ I think the three are very similar. Though the saber is better for slashing and it's usually curved back then.
So it's the most different since the rapier goes more for thrusting.
Epee has a sharp point and I think it's kind shorter than a rapier. But foil has a blunt point.
So epee is probably the closest. I believe it's a direct descendent since the rapier was just shortened to make the rapier