I have a classic swat and really like it since it's something different than an AR and has been reliable. Recoil is very mild, even less than an AR. It's more of a push and no spoing in the stock.
It does have a few issues/draw backs, but most can be cured with $. It is a bit front heavy and clunky, especially with the aluminum quad rail. I put a forward pistol grip on mine to improve handling, especially since the quad rail forend is so fat when the rail covers are installed. I didn't like the factory sliding folding stock since it was very rattly with a lot of play in it. I bought an aluminum folding AR stock adapter and put a Magpul CTR stock on it. The rear diopter site had a lot of play but I cured that with some duct tape on the rail to tighten it up. I have since removed it to put a mini ACOG on it. The original SIG mags were crap and made the thing jam constantly, but I haven't had an issue since using GI mags.
Overall, if I had to choose only between an AR and the 556, I'd go with the AR since a bit more ergonomic, lighter and parts are more common. The 556 does make a nice addition to a collection and if it were the only thing available as a "go to" gun, I wouldn't feel undergunned.