I collect Airsporters and I think I own all the models from Mk1 to Mk6 and a late Mk2 'S' Airsporter , but it depends what you want to do with it.

For practicality if you can find one is the RB2 models, but they are getting harder to find in good condition.. Otherwise a MK2 with later two piece scope rails. Very few got anywhere near the legal limit by the way, although my Dads mk1 I used successfully shooting everything legal with in the 70's, turned out to only be 7ft/lbs when I checked it.

If you seriously want to hunt then buy a Pro sport or TX200 or HW77 preferably in .177. I compete in HFT occasionally with a Pro sport, and it is what the Airsporter should have been, the rest of the time I put my sensible head on and use a Steyr LG110.