TM external backups
I'm one of those guys who religiously backs up externally with TM, as well as clone copies with CCC. As my iMac is a late 2013 model, both TM and CCC backups are close to full and I plan to safely delete the backups, reformat the drives and start backups all over.
In this regard, the iMac has been formatted APFS and is running Mojave 10.14.6. Both external backup drives are formatted Mac OS Extended (Journaled). While I am starting fresh, should I reformat these external drives APFS or keep them Extended (Journaled)?
I feel pretty good deleting these backups as I have only gone to the TM backup once since 2013 to restore a file to my main drive. All other activity has been simply backing up.
Thanks in advance for any help or recommendations provided.
iMac 27″, macOS 10.14