Take this comparison based on a year old leaf (so some tire wear and car "settling") versus a new volt:
Handling: I think the leaf handles better than the volt. I can take turns tighter on my winding "S" road home. The volt feels like its about to slip if I go to fast, the leaf never feels like its slipping around the S curves, and although you would think it would tip (like all taller vehicles), but it doesn't even come close to feeling like its tipping. But this is a very very small detail versus both. Both handle extremely well.
Other: I believe both cars handle bumps quite well. While the volt feels better now, I believe its due to the leaf's tires having almost 20k of tread life removed. Based on the begining experience, I would say the leaf edges out the volt. The leaf handles road noise better than the volt, but its really close - both do it quite well. The battery and range prediction on the volt is far superior than the leaf. It's estimates are not only better, they flucuate less (even on the highways), and we constantly get range over the EPA AND the LA4 cycle range (driving normal). In the leaf, I beat the EPA, but never really come close to the LA4 cycle range. Charging port access goes to the Volt, either via remote (AWESOME!) or a nice easy-to-access button on the door. The J1772 port location is all for the leaf. The front port is so easy for access. In addition, the port is slightly angled up so the j1772 plug goes in easy, the volt has a flat angle in which can make it slighly difficult to plug in.
Interior: The volt is definetely more luxurious, and, especially with the upgraded speakers, better sound (alot better). I find the cluster button console on the volt to be a bit daughting and complicated, but it adds more functionality; the leaf is more intuative and easier to navigate but offers less options (think of android versus iOS). For display options on car info (specially battery and output), props goes to the leaf. A full engine and usage readout of power is wonderful and the bubble icon for regen and acceleration is way better for minute control versus the leaves/bubble on the volt (almost useless imo for micromanagement). The display is more "slick" and upscale looking on the Volt, but it doesn't give the feedback I want that the leaf does.
Apps: The volt app is better than the leaf. I really like the extra info: tire pressure, oil, etc. There is more information here than the leaf. Always having to sign into the leaf app = crap.