FFP
Tracking/RTZ
Zero stop
Optical quality
Weight
Mag range
Reticle
Eye box/Relief
Price
I don't own any cheap scopes anymore. I have upgraded over the years to all top tier scopes. Well worth the cost in my opinion. But I shoot...a lot. Good investment.
Once you get into top tier, the first 4 items on my list are a given. So the next 5 items are really where my choices and concessions start. There really is no "Perfect" scope out yet.
Tangent Theta glass, turrets, parallax
March anti-glare, mag range, weight, zero stop set
S&B 5-20US length, daytime bright illumination, low profile turrets, locking turrets
Kahles reticle (SKMR for my tastes)
USO or ZCO internal level
Vortex warranty
Vortex Diamondback price!!!