For centerfire scopes, parallax starts becoming an issue around 10X magnification. The factories normally set the scopes parallax free at 100-150 yds. (depending on mfg).
If you're going to be doing a lot of load work and shooting past 10X, an A.O. is a good idea. If the scope is going to be used for what I'd term 'normal' hunting duties and yardages, my advice is that you'll be fine. Side focus is the 'a.o.', if you will. The scopes with a true A.O. move a lens at the objective end to clear the parallax while the side focus scopes accomplish the same thing by moving a smaller lens along the length of the scope tube.
If the a.o. is what you want to go with, take a look at their 3-12 a.o. model. The mounting distance is pretty short on these so make sure that will work for 'ya......not sure what type of rig you're working with.
And half a 'c' note back on a great scope isn't hard to take, either..........