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.
“Bid Time Return” (a.k.a. Somewhere in Time). By Richard Matheson*
The book is good, and actually the 1980 Movie adaptation starring Christopher Reeve, is excellent.
Most unique time travel mechanic I’ve ever seen. It’s so good I don’t even want to spoil it here if you don’t know. It’s a great read (or watch if you don’t have time).
*Yes, that Richard Matheson, who also did ‘I Am Legend’, ‘Duel’ (which started Spielberg’s career), ‘The Shrinking Man’, ‘Button Button’ (aka The Box), ‘What Dreams May Come’, and many more.