First of all what is your purpose for purchase. These are all different pistols for different skills. You want a target pistol, a hunter, or a gun for fast action point and shoot skills similar to what you carry?
Sr22 is a nice Little trainer for carry guns. Mine has been exceptionally reliable for years, have owed on since they first came out. The Taurus is a really nice gun as well and know of at least 5 folks from my club that have not had any issues at all. Typical internet gossip starts with one poster with a problem and then Parroted talk snowballs like crazy.
The Ruger IV and the Smith will be totally opinionated. Both having pros and cons. Personally I do not want a heavy gun for a trainer. Makes no sense if you do not carry a big gun.
And there are a lot of other 22.cals to choose from. Some of the 1911's are fun as heck.
And want real fun? Develop a lot of great fast action shooting and totally reliable? Get a LCR22.