Of those two, I'd have to vote for the Ruger Mk III or 22/45. Either one will be more than accurate enough to shoot NRA bullseye, and with care, last a lifetime. If you think you'd like to change grips or internal parts to improve the trigger, than I'd vote for the Mk series. Many more accessories out there than for the 22/45 so far.
The Smith 22A isn't a bad choice, but not quite the equal.
Not much I don't agree with cept one thing.......... There are just as many if not more accessories for the new 22/45's than the standard MKIII. It's what happens when you swipe the grip panels off of one of america's most beloved centerfire handguns.