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.
I haven’t read any of her other books even though I liked The doomsday book. The reason is that I didn’t like the fact that the main sort of plot in the future revolved around missing phone calls. Because all they had was landlines and the fact that no one manned such an important phone constantly or that she had at least thought of some kind of technology that could work, since they had managed to build a time machine, but apparently not thought it troublesome enough to do anything about long distance communication in their own time 😅 but I can safely read her other books then ?