10 minute and above, also any time control with a large increment. Although i have faced some players in blitz recently that have been banned for fair play violations so people like that still exist in short time controls.
Cheaters: most likely time control?

Has to be rapid, I think it would be hard for cheaters to keep up with the faster time controls like bullet with their engine assistance, although I can see 3 minute and 5 minute blitz having some cheaters. At the same time, those fast time controls could be more of an appeal to cheaters because people would be less suspicious of using cheats in such a fast time control.

https://support.chess.com/article/648-what-do-i-need-to-know-about-fair-play-on-chess-com
https://www.chess.com/article/view/online-chess-cheating
https://www.chess.com/article/view/chesscom-update-march-2024#FairPlay
The site closed 57,000 accounts last month for fair play violations and has a full team of staff working on reports along with some automated systems for detection.
https://www.chess.com/article/view/fair-play
That said, discussions of cheating, potential cheating, or cheat detection are not allowed in the general forums. If you would like to discuss join the following club. https://www.chess.com/club/cheating-forum
Which time control do you think cheaters are most likely to use?
Does anyone play certain time controls to try to avoid encountering cheaters?