110 if you want lifetime guarantee, 70 if you want their best headset without the lifetime guarantee, 40 if you're on a budget but would like a decent headset.
I use a 40, but I am a bit of a tight arse.
Just clean the seals every so often, and whichever one you get should last a good while.
Actual benefits by going with a Cane Creek Hellbender 70 or 110 over a 40?
Would actually be used in wet/muddy/bad conditions year round.