Burris Fullfield II. Amazing low light clarity. Forever warranty. Can be had for $200 or less if you look. Important thing is the objective lens size...if you want to be able to see in low light conditions you need at least a 40mm objective lens IMHO.
"Keep your nose in the wind and your eye along the skyline.'
At 300 yards it might be worth the extra zoom. I hunt with mine on 4 power and shoot my deer within 50 yards so I haven't needed much zoom but if you like hunting open areas there is no downside to the 4-12 except price.