I've been using the Moon+ reader for the past couple of years since moving over to Android. They have a free and paid version and, for me, it was well worth the $4-5 I paid for it. It organizes the books very well, keeps track of what you're reading, gives a pretty decent replication of book reading and page turning. The free version is ad supported.
It does take a small bit of working out to get it to work well with KitKat if you keep your ebooks on your SD card. If you keep them all on your devices internal memory, you won't have issues. Really the only issue with KK is that you have to manually point the directory to the folder and it'll import them from there. You'll have to manual transfer the books to the folder on the SD card but the import feature brings it right to your bookshelf to read.
Tech support is an email away and the few times I've had questions, they've been replied to within a few short hours of posting, sometimes sooner.