If you like your buddy’s exo start there. If the hip belt is comfortable under load that’s the most important to me. Next is bag layout and bag access. I like a panel load style or side zipper, but some like top access only. Exo, SG, Kifaru will all outlast your use and I think they all have a reasonable return policy so you might just be out shipping if you order and don’t like a pack. It is also worth your time to call whoever you’re interested in buying from. They might be able to shed light on features you don’t even know you can’t live without.I only spend about 20-30 days of actual hunting with the pack so assuming it'll last me a long time. I ruck with it once or twice a week year round with weight as it keeps me in shape and I enjoy it, so it gets pretty gross from that, but easily washed out once or twice a year.
For those who are upgrading, but don't have the option to try on before you buy, do you just order a few and then sell the ones you don't use second hand or just buy one based on recommendations and research?