Hi Coach 88
I've got Book Reader for EPUB and Kindle Books by Untangled Development. My Aus version costs $1.00 as showing on PB Appworld.
I find the app good enough for my needs and do all my non PDF reading using it.
I've also got Pdf Reader by Sporadic Software, showing as AUD 1.00, to read all PDF docs.
And that also is a very competent reader.
I'm sure you realise that your books will need to be DRM free in order to be read.
Let me know how you go .....