Update Mar 31 2014: Readmill has announced they will shut down. Sad, sad, sad news. Might have to go back to Kobo or find a new one.
I like to read once in a while and for a long time, I have been using Kobo. It works pretty OK. Neat UI, nice social media features, achievements to encourage you to read, and a nice widget. The only problem I have with it right now is it can't find the epub files on my phone. I'm not sure why. It could be the Android 4.4 KitKat ROM I am using since that's the only variable that changed since the last time it worked (was on an Android JB 4.3 ROM before that). Now how am I supposed to read my ebooks if it can't find it, no?
Last night, I stumbled on Readmill. And it is an answer to my prayers. Wink. It may not have social media features and achievements (yet) but immediately fell in love with the really clean and minimalist UI.
Unfortunately, it had the same issue with Kobo: it couldn't discover epub files on my phone. Must really be the ROM I'm on. But how did it solve the problem? It has a really convenient web library sync feature. You simply go on their website, sign in, and upload your DRM-free epub files there and then trigger the sync from the phone app. Voila, I won't have to manually re-import my books again between ROM system formats. Yey!
Although it doesn't have the widget feature and footnote links don't work, the UI and web sync totally won me over. Will be sticking with this for a while. Try it out.