one problem with ranking leagues based on the level the player comes from is that a 93MPH mid-major scores lower than an 85MPH bench player from a P5. same goes for a C that rakes at mid-major vs a bullpen catcher with a great GPA at a P5 who can't hit a lick. lots of other scenarios like that. especially with the prevalence of transferring going on. but I don't think anybody has a better objective way of way of ranking leagues.
the Savannah Bananas are a completely different experience than the Alaska League and some players will love one and hate the other. The fields at the Cape might disappoint some kids. etc. it all depends on what you are trying to get out of your summer experience.