The most durable plane is the one that doesn't crash. But if like me, you don't live in that universe, here are a couple that can take an extreme amount of abuse and still come back for more:
+1 for the HZ Super Cub
Anything like the Sky Surfer/Bixler, Wild Hawk, Multiplex and on and on...
+1 for the HZ Mini Cub
Don't leave out the HZ Champ! We've beat the living crap out of these things at my school. They just keep going!
Buy packaging tape and Gorilla Glue by the case. They have magical restorative powers.