At my range, there are 2 owners of the Sig 522, one owner of the Mossberg Tactical 22, two GSG-5 22's, one GSG AK47 22 and about 5 of us with the S&W 15-22.

I have been able to test each of these rifles at 25 yards.

I found the Mossberg, SIG and S&W to be fairly equal in the accuracy department at that range. The GSG's are strong performers, however, I did not want an HK or AR look. The Mossberg is AR looking but in fact has some departure points in its design like the molded in handle for one.

The SIG and Mossberg have very large magazines as far as width is concerned and the GSG has a very small magazine in size

I chose the S&W 15-22 over the four of those other rifles.
I have some latent knowledge on the AR platform, so the learning curve on trigger and rail parts was considered a plus for the S&W.
Pretty glad I did. Mine has been a flawless performer over 2000+ rounds and quite accurate at 25 and 50 yard ranges.