Idk all about the winter tires if your driving an X... id def get winter tires for the RWD... but i have all seasonal tires and they slip a bit in the rain/snow but much better than any RWD would handle

 

If you're ok with an automatic transmission and have to drive in snow/ice, you might as well get the AWD.

If you want 3 pedals, get the RWD and some snow tires.

As far as all-season tires go, they're generally ok in all driving conditions but they don't excel at anything.

Ice/snow - snow tires rule, all-seasons are functional, and summer tires suck

Rain - all-seasons are functional, summers rule (there's a common misconception that all-season tires are better than a good high-performance summer tire for wet roads - FALSE!)

Dry - obviously summer tires are the best

Check out a comparison Car and Driver did for all 3 types:

C & D

 

The AWD system is an amazing set up that has been race tested by Nissan for about the past two decades. With that said, it's almost too good if you like the feel of a RWD car and the way the back end traction can be controlled with throttle. I drive an 05x, and it seems as though you just cannot get yourself in trouble with this system no matter what the conditions. I've gotten so used to how effective it is on wet pavement, heavy rain, and snow, that I think I would scare myself without it. It's crippled my skills with its awesomeness.