No way would I buy an S&B 5-25 at new prices when the new 6-36 is available... and this is coming from someone who picked up his first S&B 5-25 about 12 years ago and then promptly bought 5 more and still uses them frequently and likes them.
A used 5-25 at $2250ish sure... but no way would I recommend buying a 5-25 at new prices, you're essentially paying today's premium scope prices for yesterday's premium scope design.
Sure you can get the new excellent DTII+ turrets on a current production 5-25 which brings at least the turrets up to date, but with the 6-36 being a better scope in practically every way and being about the same price I have no idea why you would pick the 5-25 over the 6-36 if buying new.
DTII+ turrets are the way to go unless you need to use all the elevation travel in the scope for ELR, in which case look at the MT turrets. They're a bit busy but you can use all the elevation in the scope, whereas the DT turrets stop after the second revolution even if there's still available elevation erector travel.
Regarding the atacr, hard pass on the 5-25 atacr, I was not impressed with the one I had and sold it about a month after buying it, the glass wasn't on par with the price of the scope. Far prefer my S&B 5-25s to the atacr 5-25. The 7-35 atacr is far better optically than the 5-25 atacr and would be the one to get.
In the same price range, you might also consider a used ZCO 527 or Tangent 5-25.
Also, even though you didn't mention it I have to say give some consideration to the razor G3 6-36 as well. Even though I have several S&B 5-25s and 3-20s as well as several Tangent, premier, and minox 5-25s and that's all I've ran for years, I decided to try a G3 last year and was impressed enough I now have 3 of them and am thinking about picking up #4. They're good scopes, good enough they make me question if it's really worth paying $1000+ more for the incremental gains the alpha scopes offer over the G3.
I've looked through, but have yet to buy a ZCO 527 and spend extended time using one, but by all accounts they are excellent. I've been impressed with the ZCOs I've looked through and taken a few shots with.