I have all you have listed. Honestly the mk5hd 3.6-18x44 pr1-moa illum and the soon the be released pr1-mil illum is the only scope where you'll actually be able to use and clearly see the reticle on all magnification levels. The scope is compact, lightish, locking elev, covered windage, the only downfall, the glass in the 3.6-18x44 mk5hd has a lot of variance from sample to sample, whereas the 5-25, 7-35 models are consistent, and on average, better than the 3.6-18x44 model. If you're considering a kahles k624i, might as well consider a mk5hd 5-25x56 in the pr1-moa or coming mil versions.
The March 3-24x42moa(my particular March) is basically a duplex 6x on down. Anything above 21x the fov darkens dramatically, plus the eyebox and parallax are super sensitive on this optic. If you jump to the 52mm objective the darkening in upper mag range is a lil less, and eyebox is slightly less finicky, but parallax still a bitch. Teuurets and zero stop are tits, it cuts glare as good as a theta, and is the lightest most compact of all the options.
The kahles? Man I love this scope, I have 4x 3rd gen k624i. The glass is great, turrets, ambi parallax, left windage, tracking, they just feel great. BUT the reticles are pretty small on 6x, they're long and fairly heavy at 31oz. My eyes do not notice CA, and the k624i does have it so I'm lucky, but a lot of people do. So that can be a drawback.
I'm a big fan of the nx8 4-32x50, have a couple. They suffer from a little of the eyebox parallax issues that March has due to the same short tube 8x erector setup, but it's not as severe. The NF reticles are better, and glass is very clear in the center, the edges aren't as clear, but you have to make a tradeoff somewhere. Supposedly NF is releasing an atacr 4-20 this year built off the 4-16 body, it'll still be a 30oz scope, it'll be a dn good one though.
Best of luck and hope my rambling gives you some usable insight.