I had a similar experience. Back before epub took off, I started reading Gutenberg books on my wince phone. I think I was using an app called jbookshelf. Even then I loved the convenience of it.
Once android happened, I switched to epubs and it was so much better.
Now I’m mostly using koreader, along with kindle and Google play books. I prefer reading anything in a foreign language on Kindle, because it’s so easy to look up words.