Sounds to me like you just need to decide which is more important to you. Either its the Amazon CS, and general reliability of Kindle software, or the bigger screen and better customisation options you'll get with the Kobo?
The Voyage is a little more expensive, is that extra cost worth considering, which'll maybe edge you in favour of the H2O? Also worth thinking about is if you are buying online, while the Voyage seems to have a lot more issues than the H2O with quality control (i.e. there are a few with yellow tinged screens -
see this post showing an image of a 'bad' and 'good' version). If you have any need to return one, it'll be a far easier experience doing so with Amazon than with Kobo.
Both look very good and you'd probably be happy with either of them. In saying that, if you are struggling to decide between them, although you've said you are happy to convert, as someone coming from an epub ereader, just for pure convenience, you'd probably be as well to go with the H2O.