The side focus are heavier, and some/most have the problem of not being able to dial out parallax and focus at the same time. If it were me, I'd go with the AO. And before you buy, see if you can get a look at the new Sightron silhouette scope they just unveiled at the SHOT show. 6-24, AO, 1/4 minute clicks, and 1/2 MOA dot. I think it's going to be my next sil. scope, and I've been a Leupold fan for years!