I have 4 Ruger 22/45's and 2 Browning Buckmarks (a Hunter and a Challenge). I love the 22/45's - they field strip and reassemble very easily once you get the hang of it, and I like that you can do it without tools. The only think I don't like is the cheap feel of plastic frame and integral grips. The Lite model I have with the plastic frame and replaceable grip panels feels much better. Ruger doesn't sell that grip with a stainless target barrel though, so I mix and match grips and barrels a bit. I think the metal frame and grips of the regular Mark I/II/III models would feel much more solid, but I wanted to use these to train for my 1911's. It did take me a while to get used to letting go of the bolt like a sling shot, instead of easing it down and getting my fingers pinched. I do like to tinker with my guns though, and have one of them down to a 1.5 pound trigger pull.
I love shooting my 2 Buckmarks as well. They feel much more solid, and are just as accurate. The big bull barrel of the Hunter model barely moves under recoil. The only negatives is the need to use an allan key to field strip them. It does seems to hold zero fairly well on the red dot I have mounted. The other thing I have noticed is that my left thumb gets pretty dirty with the exhaust gasses from blowback of the bulk 22 ammo I use, and occasionally I have felt odd bits of hot debris hit my thumb.
So net is, I don't find any difference in accuracy between the Ruger and the Buckmark, and each has their benefits and foibles. If I had to do it all again, I'd get a Volquartsen 22/45 metal frame and slap a target bull bull barrel on top of that. Or just get a complete 22/45 setup from Volquartsen if they would ship that up here.