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 Tine Travellers Wife
I havnt looked in comments so it is probably listed a million times but for me, the way it’s told from the wifes perspective and the ending make it more than just a “time travel” sci fi.
We always think about ourselves travelling and what we would do, the issues of how much time will have/not have passed on our return (and the science of it), and the experiences travelling would bring… But this book shows what its like to be the one who cannot go with someone who can, and how life is naviagted when you have agreed to be with someone who can.
One of my fave reads of all time. So visceral.