new normal
The old standby 3x9x40mm is now probably overshadowed by the 4x12x40mm. The 4x12 family is likely the new normal.
If one can use the extra magnification, why not? As long as the objective bell does not get on the overly large size, the 4x12x40's I've looked at seem OK.
I'm not so sure that most of us need 30mm or larger tubes, or objective bells much larger than 42-44MM. And in my mind, an AO just adds more weight and bulk on a hunting scope, used to distances around 300 -400 yds, and requires a higher set of rings to boot. I'm of the same opinion on target/varmint turrets too. Avoiding all that hardware, and keeping the objective bell a reasonable size, will go a long way to keep scope weight and bulk down.
Note I am referring to a big game scope and not a target, varmint, tactical rig.