I am in the process of collecting the parts for my 2" spacer lift project.  I only need front struts now.  Advance has KYBs and Monroe sensitracs for about the same price. 
Both struts have lifetime warranties.

Which ones would be better for offroading?  Last longer?

Thanks

Jon

Bilstien. 

For bolt on reliability Bilstien struts are the best you can get but they are overly expensive.  Hopefully someone else will chime in on the other two, but if they both come with a warranty then just go hit a couple washboard roads and overheat them, then exchange for the other type. 

If your going to wheel it neither are great.  I would go bilstien first and second old man emu. If I had to choose between monroe and kyb id go monroe. Kybs tend to ride harsh yet dont dampen as well as you would expect for the harsher ride.