While I do understand the rational for leasing, I'm personally still not crazy about driving a car that I don't own, and getting into perpetual payments. My feeling is that if it's not worth buying, then it's not worth getting.
From a personal finance point of view, the only LEAF I'd consider buying would be a used vehicle with a decent battery. Someone else has already taken a big depreciation hit. You should then be able to derive enough value from the car even if replacing the battery pack ends up not being a reasonable option. And you're not automatically looking to make another trip to the dealership in three years. (Car dealers love leasers...)
By the way, with decent tires, the LEAF does great on snow and ice. The low center of gravity helps handling and road adhesion, as does the smoothness with which the electric drivetrain can deliver power.
2011 LEAF at 71K miles, pre-owned 2012 Tesla S 85 at 98K miles
LEAF battery: 9/12 bars and < 49 Ah (-28% vs. new)
Tesla battery: 250+ miles of range (-5% vs. new)