It kinda depends on your priorities. If you're numero uno mission is to mimic the grip of a 1911, the Ruger 22/45 is your gun of choice. (even though they've never felt good in my hand, and I've spent quite a bit of trigger time behind a 1911) But, then if that were a priority a .22LR conversion for your 1911 would seem the way to go.
As far as Browning Vs. Ruger...well....If ya' look at the thread below I rant and rave about my Ruger Mk I quite a bit, but....that's mainly from a standpoint of sentimental value. in handling qualities, it falls far behind my wifes Micro Buckmark. In the area of inherent accuracy, it falls a smidge behind, in dependability, they're both excellent, but the nod there would go to my Ruger. For ease of maintenance the Buckmark gets a big nod over the ruger. Oh, an idiosyncracy on the buckmark is that the slide can be a bugger to cock, especially if dryfired (on empty .22 brass, so as not to damage your firing pin) The Rugers alot easier to cock, especially if you have large forepaws. As I recall, there's alot more of a gadget market aimed at the Rugers than the Buckmarks as well.
The most recent production trigger I've fired on a Ruger had a pretty rough trigger also. Whereas I've had gunsmiths look at my wifes Buckmark and wonder how the hell it got out of the factory with a trigger that light. (it is a very sweet trigger) The trigger on my buddy's Buckmark isn't much heavier.
So, here's the breakdown of my experience
Ruger- slightly more reliable, more sturdy,
Buckmark- better ergonomics (for me) and more inherently accurate (by just a little)
You really can't go wrong with either of them, about all I can say is paw 'em both at your local gun shop and see what you think.