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.
A Matter of Time by Glen Cook. A group from the future escape a world ending event and end up in the 1860s, one of them is the cause of the event and the other three are determined to preserve their future and stop him, they are trapped in a causality loop which the villain uses to try to trap them. It’s entwined with a police mystery after one of the traps attracts some attention and the personal drama of one of the police officers with a connection to the time travelers.