My pick would have to be the A Whole Nother Story trilogy, in which (spoiler warning) you can only travel back in time. But because time is in a loop of sorts, if you go before the beginning of time, you will be at the end of time. From there you can go back to any time you want to. And time paradoxes cannot be produced. Plus, your memories from the previous timeline exist as well as the memories from the new one.
it’s my favorite book, my mom gave her hardback copy to me at 14 or 15 after she read my copy of twilight before we went and seen the movie, stating simply, that was terrible this is 1000 times better.