You want to fit winter tyres to all 4 wheels.
I got some Nokian WRG2 last winter and my word they are amazing tyres.
They are normally in the top 10 tyres in winter tests but there are better ones out there for out and out snow grip but where they excel is they are truly usable in ALL conditions - including hot dry days and they last very well.
We did about 4k on them over winter and they still have the 8mm wear markers showing - most wear was encountered during a very warm March as I waited a bit late to take them off.
They are classed as an 'all weather' tyre with snow rating not an 'all seasons tyre' and to sum them up:
1. ice - I could easily drive on ice when everyone else was spinning. Yes I could still lock them up with no ABS on the car but I could instantly tell one wheel had locked up and could just modulate the brake to get control back. No drama.
2. snow - what snow? My dads car was stuck on his drive up north. I just pulled up and parked (on a hill) no problems. I actually aimed for snow mounds just for fun.
3. slush - melted snow etc that can be a real problem - none for these. They are aimed largely at slush.
4. dry roads - a little bit of noise from the blocky tread but so much grip, feedback and comfort they make my summer tyres in summer feel crappy and harsh.
5. wet roads - again 'what rain'. Almost no difference to the grip levels in wet conditions.
Only problem was as it got warm they did get a bit squishy but that is understandable with 8+ mm of winter tread (the sipes make the blocks move more) and they are obviously softer.
The comfort over bumps made my 13 year old peugeot suspension feel brand new and I got better MPG out of them (designed to be efficient).
The missus was glad when I took them off as my cornering speed is now about 10mph lower on summer tyres.
If you watch the prices closely (mytyres) they fluxuate a lot. Mine were £66 each all year then went up to £80 during the winter. One day they dropped to £50 each so I snapped them up. Next day they were £104 each. IMO they are perfect for the winters we have in the UK. You won't miss the slight lack of grip compared to the more expensive (double price) top marks winter tyres (conti and michelin) but the other benefits of dry, slush and wear performance are huge benefits.
Ps I don't work for Nokian or any tyre company. I just rate them very highly and won't run summer tyres in winter ever again.