If you shoot highpower or other bullseye event and want to be able to check your target and the mirage between shots with minimum movement, get a 45 deg model. If for metallic silhouette spotting get a straight eyepiece model. I dunno about benchrest, I find both kind of awkward.
A fixed power 25 - 27X long eye relief eyepiece will do anything necessary for the target shooter. A zoom eyepiece has a narrower field of view and cranking up the magnification is no real help on the range.
If for highpower, you need a scope stand, one of those low bipod or tripod bases with the tall single pole and the most offset scope mount available.
If for silhouette, a good heavy camera tripod will work.
