Well, Kobo helpfully uses the term "Mark" with an increasing number, so, that's easy enough on this side of the fence ;p.
It takes a little bit more effort on
Kindle 
.
TL;DR:
Kobo Mk.5: i.MX508
Kindle Wario: i.MX6SL
Strangely enough, both companies tend to use a generation switch (i.e., mark/platform) to mark a significant SoC update...

.
Do note that I've never negatively commented on how the H2O's screen *looks* (for good reason: it looks great when it's not actively doing anything). I'm concerned with how it *behaves*, which is completely different.
And that it's something I realize I may be (overly?) acutely aware of, more so than most. The same way any kind of jitter (or, conversely, badly implemented motion smoothing tech) in other screen techs drives me nuts.