Two reasons why I would prefer the Glo:
1. Kobo says the Glo has a "non-glass" screen, i.e. presumably the famous plastic substrate we're all waiting for, and so should be less fragile than the Kindle (or practically any other reader currently on the market).
2. Kobo has introduced a unique feature in their software that allows you to adjust the weight of the fonts you are using. That's great!