So most of my raft experience has either been a 15 foot Riken or a 13 foot Riken. My Dad got the 13 when I was in high school, and it has been a bomber boat. However, I'd call it a great day boat and a pig for overnoghters. Now typically our rafts turn into support boats with a mix of maybe 2-3 rafts and 4-5 kayakers, so the 2-3 rafts haul up to 8 people's gear on the Rogue, Owyhee, John Day, etc. It's a great paddle boat for 2-5 people, and fun in the big water. Loaded up, it doesn't like to move. We just recently acquired a 2008 Sotar 14 foot ST, and Dad and I have paddled it tandem a few times with great success. I R4'ed it down the Deschuttes also, with great success. It has been down the Grand Canyon twice, supporting 2 people for 18 days. (Got flipped at Lava last time!) The 15 foot raft was where it all began for me. A good friend who still is on 75% of the trips I go on started taking us when I was a little kid back in the 80's. It is too heavy for R2, but a great multiday gear boat.
After paddling the Sotar a few times and rowing it a few times, I'd call it a great balance of paddle boat and gear boat for the overnighters. It is much lighter than the either Riken, I'm not sure how it compares to the RMR for weight, but it seems to give an advantage for being a 14X7 raft that can be paddled by 2 people. Brand is up to you, but I am putting my money where my mouth is with the 14 foot size being the do all size.