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 Gift of Time by Jerry Merritt is about an old man at the end of his life that has a space alien crash land on his property. He assists her in repairing her ship, which as it turns out travels through time and space. As a reward for his assistance, he is allowed to ask for one gift. He has his current mind placed into his childhood body, so that he can be there to rescue his little brother that was kidnapped that Summer.
It’s a really good book in my opinion.
Although not exactly time travel, a similar concept is The First 15 Lives of Harry August by Claire North. It’s about a man who is effectively immortal. He dies and is immediately brought back to the beginning of his life. His conscious memory of his previous lives comes back when a child begins to have self-consciousness at around 3 years old.
Really interesting Time Loop type story.
I was looking for this answer, A Gift of Time is one of my favorites.
I got into a streak of time travel books because of A Gift of Time.
I also recommend The Outcasts of Time by Ian Mortimer. It’s about two brothers in the 1300’s at the height of the Black Plague. Death comes to them and tells them, they can either continue on their lives and die in a few days, or they can live their remaining few days, but wake up each day 100 years into the future for each waking.
It has a lot of religious stuff, which even as someone that isn’t religious, I didn’t find to be too much. It was one person firm in his beliefs talking about them with someone that was of the same faith, so it didn’t feel preachy or like it was trying to convert me or overwhelm me.
But it was a really good story.