Gun Tests Magazine performed an assessment of the Smith & Wesson M&P 15-22 and Ruger’s SR-22 in their February 2010 issue (Tactical-Style 22 LR Carbines: Ruger, S&W, Legacy Duke It Out). They rated the M&P with an "A" and the Ruger with an "A-". The Ruger has a higher cost compared to the M&P. The article in Gun Test also noted that the Ruger did not come with sights while the M&P did. The M&P provides the function and feel of the AR-15 platform. The SR22 provides a tactical look but is based upon the 10/22. Ultimately, it comes down to what it is you are looking to accomplish and which one best fits your purposes/expectations. Keep in mind that the Ruger 10/22 carbine can usually be purchased for around $200 (Dick's Sporting Goods). There are numerous modifications and enhancements available for the 10/22 including ATI stock replacements, trigger upgrades, etc. I personally have the M&P and the 10/22 - both are great guns.