I think the comment about durability is a little bit off base. I have MR pack and and SG, build quality is pretty similar although MR definitely has the upper hand on some pack models.
Biggest differences SG is $100 more, 15ish% lighter, 15ish% bigger, but it has a super sparse design without any internal pockets, water bottle holders, etc. The mystery ranch is a great hunting pack for people who like the traditional pack design/organization, the stone glacier is more geared towards someone who wants a bomber pack with no frills.
Seek Outside, Exo, Kifaru, are all in the same class of pack, kuiu and outdoorman's are a step down but good. If you are 6'3" build like shit house and expect to be packing moose quarters bone in don't screw around and get a barney's. I'm 6' 150lbs and when I put on a barney's I felt like a 10yr old wearing around his dads shirt... those things are built for ogres.
Biggest thing to remember is everyone is going to have an opinion and because packs are 1. Expensive and 2. Will last forever (so you aren't buying lots of packs), and 3. They probably just bought the pack that they could try on, ie was made in their state... CO guys like Kifaru and Seek, MT guys like MR and SG, ID guys and WY guys love EXO... You are unlikely to talk to anyone who has actually owned more than 1 or 2 and definitely not 3 or 4 of the same manufacturing year, and people are just rooting for the pack they chose in order to justify their decision to drop an insane sum of money on a pack. Gotta keep the cognitive dissonance at bay or your are gonna be f-ed justifying your purchase to your spouse.
So in the spirit of the tribalism that we humans love to embrace: Exo sucks...boooo... what a piece of crab don't buy that garbage.