I'm a new shooter and have spent countless hours researching, talking to experienced gun guys and test driving pistols.
I narrowed it down to the Ruger Mark III (~$330 to $400) and the M&P 22 (~$440 to $500).
I had originally considered the Sig P226 Classic, or the Mosquito (since I've been lusting after Sigs and figured that it would be a good idea to get on the Sig platform so I can transition easily). But, the web chatter just isn't very favourable. Sigs are apparently picky with ammo and demand the good stuff (which kind of defeats the purpose of cheap .22LR plinking).
The Ruger is very highly reviewed (and is in fact used as the club pistol at the range I'm in the process of joining). I know it sounds vain, but I just don't like the looks of it.
I ended up with the M&P 22 because:
1. It is well-reviewed for both accuracy and ease of maintenance.
2. It is very similar to the full size, bigger bore M&P platform (so if I choose to stay with S&W I will have consistency and my training will carryover).
3. I like the way it looks and feels.
The main downsides are:
1. Magazines are hard to find. It only comes with one.
2. I'm not crazy about the sights, and getting good replacement options up here in Canada (e.g., Dawson Precision) is not easy.
That's my $0.02.