APFS has no advantage over HFS+ (macOS extended) and vice versa in terms of post-mount performance when it comes to hard disks (non-SSD drives). 

However, macOS Sierra (10.12) or older can not access APFS-formatted disks. On the other hand, though unlikely in the foreseeable future, it is possible that Apple might drop support for HFS+ in some future versions of macOS. Should this happen, you may not be able to access your hard disk in a future version of macOS if you format it in HFS+. In addition, AFPS is said to be less prone file corruption issues than HFS+. I recently had to erase everything on a HFS+ external hard disk due to corruption issues and reformat it.

In summary, if you are planning to access your hard disk from a computer running on macOS 10.12 or older, then format it with HFS+. Otherwise, go with APFS.

There are more details in the article "[APFS vs Mac OS Extended – Which Mac Disk Format Is Best](https://www.switchingtomac.com/tutorials/osx/apfs-vs-mac-os-extended-which-mac-disk-format-is-best/)" if you need more information.

P.S. If you plan to use this hard disk with Time Machine on macOS 10.15 (Catalina) or older, HFS+ would be your only option. Time Machine works with APFS only when the macOS version is macOS 11 (Big Sur) or more recent.