Actually this is kind of an apples versus oranges comaprison.
The Buckmark is an excellent and accurate pistol and the Taurus 990 is an excellent example of a .22lrf revolver.Either model will give sterling service.
I own a 990 and Ruger MK.III and a Ruger MK.22/45 MKIII. Both are excellent single action rimfire pistols.
These are two different types of firearm and two totally different trigger types and styles.
If one is used to mainly semi-auto pistols then the Buckmark would be a good choice. The Browning can be a understudy gun to other larger centerfire pistols.
The steady,smooth double action trigger pull all the way directly back until it breaks and smooth trigger follow through are paramount in shooting the revolver well. It takes much practice,dedication, and time to become proficient at it. Lots of dryfiring with snap caps for practice is suggested to get the hang of things.
If you have revolvers already, then the transition will be simpler than for a pistol only shooter. It's not to say that the revolver cannot be mastered. Just that it takes more for most shooters to get things just right.
The 990's trigger pull is a bit heavier than a center revolver's trigger pull, but it is crisp and lighter than smaller framed .22lrf revolvers. I also have a Taurus 94 with 5 inch barrel.
.22lrf revolvers have heavy and gritty trigger pulls as a rule.Granted, there are a few exceptions. Very few.
I had to work with the 94 to get a lighter trigger pull ,but not with the 990.
Accuracy with a Buckmark will be a bit better than with the 990. Both guns are usually more accurate than their owners.
I own both many pistols and revolvers and have found the Taurus lines of firearms to be very good choices. 17 Taurus revolvers and 3 Taurus pistols are in my battery. So are Glock,SIGs,Beretta,Rugers, Springfield XD, and a host of other handguns.
Go and handle, maybe shoot as many as possible and pick which gun meets your needs and wants the best. It's what fits you that matters.