These days the best removable media would be whatever is the most common and cheapest. ZIP drives came in all kinds of Macs in the PPC era and there are plenty of external SCSI models that would work on everything down to the oldest SCSI compact mac. I had zip disks with data from back to the mid 1990's and they still work fine, never had a click of death drive yet.

I do like the old Syquest 88MB drives as well as a few types of MO drives, they are easy to install since they are all SCSI and work like a normal HD would.

As far as reliability goes, if you are just using them to move files and not as long term archives then they are all fine. Nothing of that era beats MO media for archives.