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.
The End of Eternity by Asimov
I was looking for this one! This is one of my absolute favorite books, period, not just sci fi.
Me too!! This is one of his lesser known novels but I think it’s incredible.
The best time travel book
Basically, almost every single later work featuring an organisation that does time travel is just doing variations on End of Eternity.