.22's
Since we're in the semi forum, I'll try and stay with those actions, but I may digress a bit. Somebody is bound to ask, "best at what?" and "what is the intended use?"
Pedestrian and Fudd-like (that's me) the tried and true Ruger 10-22 has become iconic in the .22 world. The base model carbine has sold a zillion units, has a stellar reputation for reliability, and is relatively affordable considering prices these days. It can be customized to look like a space gun, or you can keep it plain vanilla. There is a world of high quality aftermarket parts to milk the best possible accuracy from the platform. A wide variety of models (9) is available from the manufacturer, to include take-downs. No, it is not tacticool or resemble an AR or an MP5, but I'm willing to bet my next check that one will shoot circles and run rings around either of the above.
The Browning .22 (SA-22) has a cult like following and is a noted step up in class and appearance......and price. Blue steel and walnut, it is Fudd-like as well, but remains popular . It was introduced in 1914 and is still in production. I've never owned one.....but craved same since I knew what they were.