I put a Volquartsen 10/22 kit (Target Hammer & Hammer Bushings & springs & shims) in both of my 10/22s. I installed them myself in about 20 minutes following the video provided on the website.
http://michigancenteroutdoors.com/volquartsen.html (scroll down a bit to see it)
Made the triggers pretty nice with a pull around 2.5-3#. Pretty nice upgrade for $45, and I've never been tempted to buy the $200 drop-in triggers I see. I guess there are Ruger's own BX triggers for about $75, but it's a little off-putting to me that if Ruger can make a nice trigger group for the 10/22 that they don't just put them in the gun in the first place.
I can't comment on many barrels. I got a Butler Creek carbon fiber bull barrel once, and it was awful. Much worse accuracy than the factory sporter barrel. I went back to the factory barrel and stayed with it, since it's good enough for my plinking and small game hunting.
In the past year I got this barrel:
http://www.tacticalinc.com/blue-116...el-for-1022®-with-thread-protector-p-561.html
I got it because I wanted a gun that was a little shorter and lighter for a youngster to use (shaves off two inches and half a pound). I never tested it for serious accuracy, but I'd say it shoots at least as well as the factory barrels.
I attended one of those Project Appleseed events once and the instructors said that a lot people underestimate the accuracy of the factory barrels, and that they should try them out with a few kinds of ammo before assuming they need to buy an aftermarket barrel that costs as much as the gun.
As for stocks, I don't like the factory wood stocks, which, for me, are too short, too slick, and have too much drop to maintain a cheek weld when using optics. I have a Hogue stock on one 10/22, and I like the look and feel of it. I've read that it's not rigid enough to work for a target gun, but, again, I don't use my guns for serious target shooting.
My other 10/22 wears an ATI stock that is probably similar to the Tapco you mentioned. I like being able to adjust the length of pull (this stock is paired with the lighter barrel for the young shooter to use) and the comb height, but the adjustable buttstock has a little wobble, which probably doesn't help accuracy. Not sure if the Tapco would be like that too. I have a little red dot on it and just use it for plinking around 25 yards mostly.