Do new M1 Macs use APFS? Creating a new Time Machine Backup drive; should I use APFS?

I'm backing up an iMac Late 2015 (Intel) running Big Sur to a new hard drive I need to format first to then create a Time Machine backup. I plan on upgrading to an M-whatever iMac as soon as they come out using Apple silicon, and use this backup drive with that new machine. Would it be smarter/better/more forward thinking to format the Time Machine backup drive in APFS, or should I use HFS+? (Or another format I'm missing?) Thanks in advance! Note: my current iMac is formatted in APFS, so I'm leaning that way.