The Zeiss Conquest is what I would recommend in your price range. I have one. I have not had it long enough to know if it will hold up for years and years. It sits on a 50 cal. muzzle loader which I load to about the max. I shoot a good bit at the range and have taken 11 deer with it. It has seen a good deal of recoil and held up well. Probably 300 rounds. It is clear and crisp to the edges and does a good job in low light. I have had no problems at all with the scope. Two of my buddies have one as well and they too are very pleased.

As far as "power" ... for me, anything above 6X is plenty for 300 yard shots at deer sized game. Most of my variable scopes top out at 10X and I have had no problems with the sight picture at 9X-10X at what is long range for me .... that being 400-450 yards. I have one that goes to 12X but cannot recall ever adjusting it that high.