I know this is an an older post but just wanted to through my 2 cents in. I was in the same dilemna a while back. And looked at all of them, with the exception of the H&K, never saw that one before. I finally decided to go with a basic ruger 10/22 and added an Promag Archangel stock. It can handle a bull barrel when I finally upgrade to one. Its pretty nice, and you can grab it for about 100 bucks. Replacing the stock on a 10/22 is extremely simple. And as mentioned ealier, the 10/22 has so many extras out there, it will make your head spin.
For the 10/22 stocks:
On the lower end of the price range you have your TAPCO stocks, two different styles with the T6 being better methinks. And the Promags, various styles with the Archangel being the AR type.
Farther up you have the ProMag Marauder which looks like a SCAR-L, complete with a magazine cover.
Then comes the Troy Industries TRX Extreme. A nice looking AR type stock with full length top rail, but its pricey.
Finally the Nodic components kit. It turns your 10/22 into a .22 caliber AR-15 able to handle any AR-15 pistol grip, stock and forearm.
The Ruger SR-22 AR type rifle is basically a 10/22 in a fancy stock and is less than 500. It will accept 10/22 upgrades, including Volquartsen and Timney triggers.
Here's my 10/22 on the Archangel - dubbed Diller Killer. (poor picture - my apologies)
Hope this helps if you havent gotten you one already.