I've got two, a Mystery Ranch NICE / 5000 and a Cabela's Extreme Alaskan Outfitter.
The MR: My favourite of the two. I should have bout the bigger bag (I think its a 6500), but mine is great for 5-ish day solo trips. The pack is definitley on the heavy side when empty, but I expect it will last as long as me. Whether empty or at full load, the pack clamps around me and never shifts. I've gotton through some scary scrambles with a 50-lb pack - stuff that I probably wouldn't do with my other one. Another great thing about the MR is that the 'daypack lid' can be snapped onto the NICE frame and used as a small daypack. This way, if things go well, you still have a stiff frame that you can strap horns and game bags to.
The Cabela's: Its a true external frame pack, and very light. It doesn't feel quite as 'snug' against me as the MR. It is a bigger pack though, and for carrying a large, awkward load out, I like it best.
I realize tht the majority of the time I spend packback hunting is not actually packing meat/horns out, but rather carrying my home and food around the mountains. Also, when you have meat and horns on your back, nothing can really bother you, so who cares anyway. My MR is perfect for the actual hunt, and will do the trick packing out as well.