Since you said 100-150yrd varminting, I'd look for a 4-12x, 4.5-14x, or 4-16x magnification scope in a 44 or 50mm objective, preferably a 30mm tube.

The extra FOV of a 44mm or 50mm objective is nice when you're looking for small targets downrange, and pulls up extra light for you for dawn or dusk hunting - especially in the 30mm tube.

The 4x bottom end will give you plenty of FOV for short range work, but having the extra magnification of 12x up to 16x at the high end will help focus in on little varmints way out there at 150yrds, further if you so desire.