Buckmark Plus w/the rosewood grips is the more refined of the 2, has (IMHO) better stock trigger, *proper* placement of the controls (for a 1911/BHP/CZ type person), more *realsitic* balance (again, for a basic 1911 type person), more open breech area (cuts down on fouling), is more out of the box accurate (based on my experience w/4 Rugers and 3/Buckmarks)<-- not a large sampling, but larger than the usual "I have a Mark II that's a super-shooter,,,,umm, never shot a Buckmark though"or "I had A Buckmark and traded it away for A Mark II", is more comfortable for >500 round sessions (@ ~ 400 + rounds I find the takedown lever of the Ruger creates a "hot spot" on the web of my hand.) For me anyhow, the Buckmark has better stock sights and lastly, the Buckmark Plus is just uncommon enough to be a little bit "special".
Not all "Rosey-wood" though. Buckmarks have a tendancy to have their hex head rail screws work loose, have numerous pieces-parts under the right grip,<-- mine anyhow have a nasty tendancy to collect crud there that interfered with the disconnect. Forntunatly, it's preventable if you keep it clean. They also can malfunction and fail to feed if you "limp wrist" it. My wife had some problems with her Buckmark Micro due to her "loose" style of gripping it. We switched over to high veloctiy ammunition and the problem disappeared. Probably the most serious problem I've had with the Buckmark(s) is the small Oh S**it clip on the slide spring. The first time I broke down my wife's Micro, that clip took off for parts unknown. It's an odd size, and I hit every hardware store in the area w/out finding one. Good news is that I found one on an old Epson printer tractor.
Ruger - fine gun. One of the all time success stories of modern industry. Without too mush fuss, they can be made to shoot very close to guns costing 2 times the price. With aftermarket trigger parts, they can be made to come close to a "very decent" trigger. HOWEVER, "very decent" is just that. Better than a stock Buckmark can be, but still a far cry from "very good" to "great". (The "Great" triggers on .22's I own are on the Smith 17's, the High Standard and ,,believe it or not,,,my wife's H&R Convertible <-- only the S/A.). Mark's are also "dump truck" tough and "junk-yard-dog" mean. For whatever reason, my Mark II slabside is kind of a lemon, and has been plagued with all sorts of small part's breakages - safety spring, firing pin spring, extractor. None have stopped it. I have no idea how long the extractor was broken before I noticed it. The gun continued to fire and spit out empties. Same with the spring on the safety. Since mine's a range only gun, I never use the safety. I also never let anyone else shoot it because of the broken safety. It was only when I was cleaning it I discovered the spring wasn't there anymore. The firing pin spring broke about 1/3 off one end. I just put the broken 2/3 up against it, and haven't had a problem with it yet.
Ok, so far it probably sounds like I'm more in favor of the Buckmark. Nope. Given the way my Ruger has performed, even with multiple broken parts, I'd have to recommend the Ruger over the Buckmark overall. Altough it's really too close to call. I guess the deciding factor would be service. Ruger has a good reputation for serviceing their products. Browning service is notoriously spotty.
OOpos. Forgot about the Red Dot. My Mark II came tapped for a rail mount. Mounting either a Red Dot or a scope was simple. IIRC, I got one of the Weaver rails from Brownells. It's low enough so that I can leave it on and still use the iron sights.