I have lots of Sightron SIII No SII, I have zero problems.
I was just talking with someone who has a SIII 10-50x60 on a 50. Says it stays together.
Today I did a little "playing" with my SIII 8-32x56. I put it in Burris Signature Zee rings, with +20 MOA added on top of the rails 25MOA. This lets me reach 400 yards with my 22LR, I'm not kidding, I reached 400 yards, dialing 72 MOA up on the SIII. I dialed back down, checked my 50 yard zero. Good to go.
Here is an idea of the tracking. 275 yards = 59MOA, 300 yards 64 MOA. 385 yards 68MOA, 400 everything that't left.
Leupold, better glass. Starts to get more spendy.
Schmidt&Bender, wow good glass, very spendy.
Nightforce uber spendy.
There are lots of other options. Redfield, Nikon. More.