I'm going to start reading again this year, it's probably been 20 years since I completed a work of fiction. I'd like to be able to do some reading across the various platforms in front of me throughout the day.

I'm interested in reading freely available (public domain?) classics. Is PDF the most common format or eBooks? I'd like to read at my desktop during the day & tablet/phone (or kindle) at night.

I'm aware of kindle as a paid solution, but not sure how well they do with classics that are freely available. Seems like they even suppress them from the store.

Thank you in advance, here's to reading 12 books in 2018!!!! :)