The best upgrade that I have ever done was to purchase the Rimfire Technologies adjustable sear, period. I threw away the Volquartsen target hammer and replaced it with the original factory hammer and trigger. I polished the factory hammer face and sear/ disconnector engagement points to a mirror finish and the trigger breaks like a glass rod. Absolutely no creep with this adjustable sear and makes the 10/22 trigger group amazing. I did install hammer bushings and the kit does come with oversized pins. It is amazing to have a 10/22 trigger wit no creep and slop. I like to burn 500 rounds through mine just for fun on an afternoon. It is the Walmart special mannlicher laminated stock stainless steel model from 1996 or so. I have a red dot on it an bought 2 tactical innovations 25 round adjustable mags. Can easily unload them in seconds with this short, predictable trigger pull.
If you are looking for a target style shooter, then barrel choices will rain supreme. Whistle Pig and Rimfire Technologies make the best there is.
I wouldn't waste money on a hammer. They are the easy way to reduce trigger pull weight but alone they do nothing for the considerable take up and creep in the group. Like I said took my Voluartsen hammer out for good. It provides a light trigger pull but nothing else. The adjustable sear is the way to go. The factory trigger will then have a solid back wall and a short predictable release. Not to mention you can unload a mag 10 times as fast when the trigger isn't traveling so much.