Free: Contests & Raffles.
You aren't going to find a lightweight pack that can handle 100+ pound loads unfortunately.I have an Exo, bought both the Kuiu and Exo and sent the Kuiu back as I didn't like the frame. I looked at Kifaru but after an hour of trying to figure out the combinations and options gave up and figured a bag with straps didn't need to be that complicated.They all have fans and are well made, it's personal preference.
Just a heads up, Exo is working on a K4 frame. It's apparently been in development for quite a while, Steve has been answering some questions about it. So if you're leaning Exo it might be worth the wait. https://www.rokslide.com/forums/threads/exo-mountain-k4.279017/I have a SG Sky 5900 on the x-curve frame. Love the way it carries weight, it packs down well for day hunts and I can fit a 6 day trip in it without the lid. It's not "lightweight" and the bag is definitely more open concept though. Some people think the padding in the hip belt and straps is a bit thin but I don't have any issues with it. I think Seek is currently making the lightest packs capable of packing out an animal with. And I hear they're pretty comfortable. But yeah, to echo OltHunter, look at Stone glacier, exo, kifaru, seek, or initial ascent.