Hardest Technic set to build?

[mocbuild101]

So far it would be 8110 for me, but that's just because it's also the biggest set I have built.

Really it's any set that is big and has PF and a lot of pneumatic, so  42043 would probably be the hardest but I haven't got/built that yet.  

[Richard Dower]

My first set was the hardest, because i had never used Lego before...never mind Technic. I was building the 9393 Pickup Truck and it took me 12 hours. But now i just fly through sets....though thr older manuals require more concentration and watching the build guide more closely.