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.
Interesting fun fact I learned on the DAVIDGERROLD forum on CompuServe in the 90’s: David Gerrold, the author, knew Heinlein, and ended up taking care of Heinlein’s cat after he died. And then the cat ran away.
That means the cat that inspired Pixel in The Cat Who Walks Through Walls disappeared and it was David Gerrold who lost Heinlein’s cat.