To be honest...I've yet to find a better optic than the Leupold Mk5/Mk6 options...I have tried a LOT of optics...PMIIs, M5XI, M7XI, NF, Burris, Vortex, Bushnel Elite...etc...the two top brands I have not tried TT or ZCO...but they are out of the price point I am willing to spend currently.
In terms of size, weight, turrets and optical performance...the Leupold Mk5/6 models are awesome.
I personally use a Mk6 3-18 with a T3 reticle and RMR piggy back in a Spuhr mount...it allows me to have 1-18X capability in a sub 12" package that weighs less than 30oz...that combination is super hard to beat...but my SCAR 20 went on a diet and shaved about 2lbs off it...so weight savings is a good thing for me...plus the Mk6 is "clone" correct if you are into that sort of thing...my load out now is the same weight as a stock 20S with no optics...#winning...
Optically I have found the Mk6 to be on par with PMII 3-20 US, NF and Vortex Razors...it has better glass than the Steiners/Burris/Bushnell Elite...
One of my favorite features is the magnification bell...there is 100% no need for a throw lever...you just grab and twist but your ocular does not move it...which is one of the most annoying things about NF I did not like as your flip cover will go with the rotation on a NF.
Diopter adjustments on the Mk6 can be very precise and locked in unlike the Mk5 and other optics...which to me is a plus.
The turrets Leupold has on optics now...the M5C2/M5C3 turrets are stupid easy to set...there is no clutches or ubber small screws to mess with...zero the scope...loosen the turret screws...dial it to 0 and you are set...