I'm with John F in the wait and see camp, particularly in terms of the software on the Kobo, and the capacitive touch screen on the Kindle PW. I have high hopes that neither will suffer any clarity issues (no concerns were raised at the press conferences), and that they will be less susceptible to the problems the Nook Glowlight has suffered (Kobo have specifically mentioned theirs is more durable).
In saying that, it's a pretty low-risk gamble for people to take if they want one straight away. Sony's early attempt at lighting with the PRS-700 was a gamble, the Nook has shown screen clarity shouldn't be a problem, so now Amazon & Kobo have the advantage of being able to learn from the Nook.
However, as I've mentioned before, it's great if people do rush off and pre-order these new readers, as it gives those of us with a more cautious nature time to check out the feedback before spending our money.
