I presume you've seen this page
Kobo eReader Touch review | from TechRadar's expert reviews of Portable media players & recorders
I'd go for the 'touch' version because of it's file type capability:
ePub, PDF, JPEG, GIF, PNG, BMP, TIFF, TXT, HTML, RTF, MOBI, CBZ, CBR
and you're not tied into Amazon.