The Kobo and Sony e-reader both have excellent e-ink displays. No difference on that front. The biggest difference is the fact that the Kobo Glo has a build in light. This makes it possible to read in the dark. The following images show the difference of the screen compared to the Sony PRS-T2 with the following Kobo Glo lights settings;
- No Light
- Minimal Light (1%)
- 50% Light
- 100% Light
The photos were shot with an iPhone under poor light circumstances.
I have no problem with reading in the dark (pitch black) with the minimal light setting (1%). Just throw in more light if you need/want more contrast when reading in the dark.