[soulfuldog]

I think you would notice an improvement in the whiteness of the screen on the PW2 over the Glo (the Glo has a slightly blue tinge), but I don't think there is that much of a difference in the blackness/darkness of the fonts. Also, I don't think the screen on the Kobo Aura is quite as good as the Paperwhite.

However, the Kobo has far better font customisation options, so you should be able to fiddle with your fonts to increase the weight, sharpness etc to get something that looks as dark as possible.

Unless you particularly want to try a Kindle, if you're happy enough with your Kobo in general, I'd agree with Katsunami to an extent but say you'd be better trying the Kobo Aura HD instead of the Kobo Aura. Although it might be worth your while posting for help in the Kobo forum for the best font type to try on your Kobo Glo for readability before considering an upgrade?