I own both a 10/22 and M&P 15-22. If you are truly looking for the AR style and quality, go with the Smith and Wesson. It has a functional charging handle, magazine release, slide release, and dis-assembly, and more just like a real AR. It also has a very nice feel to it and is much more upgradable with parts for AR style carbines. The Ruger is basically a 10/22 dropped inside a stock that looks like an AR, no fun there as there are many types of stocks available for the 10/22.
When I first looked into getting a MP 15-22 I looked at all the competitors (Mossberg, Colt, Ruger, etc.) and found that the MP 15-22 was the best built, most functional, and the funnest to shoot.
The choice is yours, but I hope all of us influencing you leans you towards the right choice. Best of Luck!