I own both and love both. I have had no issues with Monarch's eyebox up to 4X12. Anything higher, I can't comment. I will say that I think Leupold wins on edge-to-edge clarity. I do think that Monarchs are as rugged, if not moreso, than any Leupold I own. I have one 2X7 that has been on everything including .375 and up to the worst kicking 12 ga. slug gun ever and its never failed. As for eyebox, the worst eyebox I've ever seen was a late '90s vintage B&L 3200 4X12.
Anyway, I've pretty much gravitated to Conquests. These are an awful lot of scope for the money.
