I think it is going to be a hard comparison. Pick the reticle you like and whether you want the heavier scope with great travel, or the one that has easier to find quality rings. We are a dealer for both. I had to come to terms with just how good the Sightron is, given their very average heritage. From all accounts, the quality of the optics are both fantastic. The decision will come down to weight, tube diameter (good and bad) and reticles.
Keep in mind, both will be outside the normal realm of production (meaning small numbers), but March is a micro producer. You might spend a week deciding, just to find out that one or neither are available. I think we have one Sightron available, and looking at distributors, it is pretty bare shelves. For March, we have a few, but ordering from March is a six month ordeal, so if we sell out, we will be out for a while. This is not unique to us, I am just giving you an example. Nightforce is a long wait as well, but a good many dealers keep a good many 7-35's, and same with Vortex and Leupold.