As far as I know, the only mainstream eink readers that let you use WiFi for anything other than buying from the integrated store and using the built in social features are the Kindle and the old nook classic. If being able to hit other Internet resources from your reader is important to you, your search can stop there.
If you're comfortable stripping DRM, then sources and formats are a non issues.
If not, then decide if the Amazon store, plus all the non-DRM sources meet your needs. If they don't and you want access to the various DRMed ePub sources, go with a non-kindle.
For me, the Internet features, including the ability to side load books over the net made the Kindle 3G an easy choice, and there is still nothing I would choose over it as my primary reader.