I have an Exo K3 and have zero complaints. Highly recommend. I don't have any experience with Stone Glacier, but have been curious about them.
I have a friend who was in a similar situation as you. He bought a pack from each company to compare side by side, made his decision, then sent the one he didn't want back. If you're going to spend that kind of money on something, I suggest you think about doing the same. Everyone's body is different and just because my Exo works great for me doesn't mean it will be great for you.
Stone Glacier's return policy reads (in part):
"If you purchased a pack, we suggest you fit it properly upon receiving it by loading the pack with 30lbs. - 40lbs. to ensure it is comfortable, fits properly, and meets your expectations."
Exo's return policy states:
"If you decide for any reason to return your pack within that 30 days, we will be glad to accept your return and issue a full refund when you ship the pack back to us in “like new” resellable condition."
It might cost you a few bucks in return shipping, but I think that is money well spent to ensure you get something you are going to be happy with.
Good luck!