If it were just me I'd take a mechanical locker rear diff 4x2 over an open diff 4x4. Basically all you have with an open diff 4x is 1 wheel in the front and 1 wheel in the back getting power, sometimes not even that. At least the mechanical locker assures you of both rears pushing.
The less weight and simplicity of the drivetrain, for the few times I'd likely ever need it, makes for that choice.
Now with all of the computerized wheel spin/traction control aids this can be different.
An older post (2013) from an auto forum said: (Begin copied post): "After having 2 different Chevy 4WD trucks running Blizzaks I found 4WD not needed most of the time, although fun. So, I went back to 2WD with 4 Bizzaks, and locking diff that the 4WD trucks didn't have. Sure it would be nice to have 4WD once in a while, but the 2WD works great with 4 winter tires. I would take a 2WD with winter tires over 4WD with regular tires any day in the snow. I can pull away from most 4WD vehicles running all seasons in the snow. Plus 4WD is no advantage for stopping and turning, which is half the battle in the winter. I like 2WD even more when the roads are clear. It mostly comes down to the right tires for the conditions, and after using winter tires every year for 20 years now, it is the ONLY way in winter!" (End copied post)
Like the guy said, a 4x2 equipped with true winter tires can better a 4x with "all-season", (which are mostly crap).
Now due to the wife driving by herself, I buy 4x auto and put weight in the bed (320# of sandbags in front of/over the rear axle, 8 bags x 40#).