Here's a summary of the available chains on the marked from my POV:
First, 9mm chains will fit a lot of cars, even those that say you can't. Experiment with a piece of 15mm dowel (chains get thrown out a bit), being particularly careful around struts, wheelarch clearances considering full load. On your own head be it though.
0 - Snow socks. Useful for emergency will cope with most ploughed trafficed roads but cannot cope with anything difficult.
1 - Basic chains. Cheap, functional, get the job done. Can be frustratingly difficult to put on especially in adverse conditions and become harder to use on repeat use. Benefit from dousing in WD40 after use. You can pay more than cheap for them too, often branded by manufacturers, best bought on the continent. Compact.
2 - Mid range self tensioning chains. Worth the extra, cost around £150, easier to fit but a true halfway house - some of the advantages of basic, some of the advantages of autofit, disadvantages of both, too, but reasonably compact.
3 - Autofit. Top end stuff, £250-£300. v easy and quick to fit, the spider type (Weissenfells / Thule are the best) will fit any car, but compromise on the grip. There's a new Thule one that I haven't tried that looks the dogs danglies, but uses 9mm chain. One big downside (apart from the cost) is the size - they are bulky.
-1 - The Mita alternative - just don't. My experience:
http://extraspecialtreat.blogspot.co.uk/2012/02/mita-tyre-chains-review-fail.htmlIf you have a big wheeled car, especially RWD, consider the more sophisticated chains, fitting ordinary ones can be exponentially difficult.