Oh well, if there ever was a good final answer to this...
However, I'll try to answer you.
It really depends on your road conditions, you say you have slushy roads.
If I draw parallels to me here in Norway, we have slushy roads in the south part of the country where they salt the roads.
And from middle to north there are less salting and more icy and snowy roads.
I have lived several years both in the thickest forest with winters with -35/40 centigrade to more coastal and southern areas with no more than -15 centigrade during wintertime.
And my findings is simple, different conditions require different tires, even if they are all wintertires.
When i lived north, I only used tires like nokian with studs and I drove alot on glassy ice on top of packed snow that's been run over. Sometimes the roads where sanded but sand often just blows away unless there's a sunny day which melts the top of ice a little to make the sand stick.
Continental was not that great at that time, but I hear it's better now, icecontact 3 seems to be fine on my family's medium size car up north.
But where the winters road conditions are are slushy "salted roads", you don't need grip, but you need channels for the slush to move away and rubber that's soft enough with lamels that can grip like several small foots in succession and increase the holding force on snow and ice when mowing over.
Where I live now, is about the same height as forth Smith in Canada.
They are salting the main highways, so they are slushy, but we have minor roads, forests and mountains that aren't salted and have just snow.
So I have best use of an non studded, lamelled, winter tire with good side stability and good channels for slush and water. This works good both in the woods on snow and the highway (120km/h) on slush.
So in order to get a tire with correct softness to work on wet/slushy roads I need an "northern European continental" tire and not an "northern Scandinavia" tire mixture.
(not to be confused with the brand continental)
So for me the tires I have had best experience with on my conditions, and bigger cars, it is Goodyear ultragrip ice.
I had and tried continental because it was great on family's smaller car (ford fokus), but was a nightmare on bigger cars in my family, (Peugeot 508, Ford mondeo, Tesla model s), no sideways stability and feels like slushing around, car feels unstable and on the edge in 70/80km/h on slushy conditions.
However, on the service van (almost 4 tons), type c tires, the continental tires works great again.
This is all a about personal preferences, driving style, etc.
But I handle all tires in the family, I think it's interesting about different shapes, rubber compounds, etc, so I always change the rubber to the right one for the person in the family, my grandma doesn't need the same tires as my uncle, or my brother, they live different and drive different. They would experience the others tires as horrible on their cars and/or where they live...
With that said, stay away from all year tires, these are the worst...
-there's a big difference in what's needed on a wet and cold VS. Wet and warm, or even just dry and warm asphalt.
My gsxr750 and dodge viper does not perform well with track tires on normal road either, requiring a different rubber and more grooves for water.
I never understood why people would have track tires on theyr motorcycle on the road, tires will never reach and hold their temperature needed for the stickiness you want in a racing tire on a normal road.
Okay, enough ranting about tires, I just find it fascinating that all contact your vehicle have with the road goes trough the tires and the contact area is about the size of your hands, and that area handling all braking, cornering and accelerations, g-forces and what not...
And no, I don't sell tires, I have a tire machine and balancer in my workshop, but this is for my own use.
