A lot of people like the Hammers 3-9x40 for durability.
I have a secondhand one that is holding up well so far on top of a couple of heavy kickers.
And a lot of people like the Hawke stuff, but some have had trouble. Your 34 is a medium recoil gun so you should be OK, and they do warranty them if it fails.
A sleeper would be certain Bushnell lines like the Trophy (when I called they told me the Trophy line was approved for springer use, but not the Banners, etc) and the new Tasco airgun line (Tasco is now owned by Bushnell and the line was developed specifically for springers, full warranty too).
I highly recommend front AO for springer, and something with drop points in the reticle is very handy for shooting stuff on the fly. Mil dots, BDC, whatever.
