IMO, main thing is to go with a fairly decent quality glass, low magnification, and prefer the smallest objective available.
The old Nikon Monarch Turkey Pro's (not made now) have a 20mm objective ---- these are my personal favorite --- very small, light, just perfect.
scn said:
I have a 2x Pentax Lightseeker with a circle and crosshair reticle that I love.
Also an excellent choice. Has a slightly larger 24mm objective, and weighs a few ounces more than the Nikon. I had one of these, and liked it. (I think these may be 2.5x instead of 2x.)
My biggest complaint about some of the new models is they have gone to larger 32mm objectives, something totally unnecessary, and just a liability on a low-power scope. Besides, we're not shooting turkey's 30 minutes before sunrise and 30 minutes after sunset ---- make the scope as small as possible.