I use the Kuiu one on my Kifaru. I found the Jimmy Tarps one loose and flimsy for my liking. My buddy has the Mystery Ranch cover with hood to prevent rain down back. Cool option but much heavier and bulkier than some. Might be nice if on a rainy hunt and traveling. Sept elk we try and get under cover and not move much in the rain if possible.
I use an Osprey model I picked up at a mountaineering store. It is large and slips on very easy. Has an elastic draw cord with tensioners at the top and bottom so you can suck it down tight around the bag. It weighs next to nothing and stuffs into a little sack that is about half the size of a cell phone.
I don't have a reckoning, but I have an Osprey cover as well that will fit around a packed Mountain Warrior. Does the job and was pretty cheap if I remember. I would have a look at the Stone Glacier one as well though.
Outdoor research makes a good one too, I use and Arc'teryx model, I have a Jimmy Tarps cover as well and at first thought it was never gonna stay on my EMR2, but it actually did hold
On beating some brush. I think with some modifications that would be a good lightweight option. The Arc'teryx one is perfect like everything they make.