Well, the ones I have just had fitted - Goodyear Cargo Vectra All- Seasons R17 103H - have the M&S symbol on them and come out in the top 3 for All Season tyres, by Independent assessors, and the only ones that do the required Load rating for the California readily available in the UK. Certainly not the cheapest but the best all round compromise.
The AA states that All Season Tyres with M&S rating are acceptable in place of Winter Tyres - as long as they are NOT Summer M&S tyres, and the Goodyear Tyres fulfil that requirement.
http://www.theaa.com/motoring_advice/overseas/snow-chains-winter-tyres.html
Tyres first - then snow chains/snow socks.