QIC-nn tape formats -- standardization???

[A J Annala]

I have an Archive VP150i DC600XTD cartridge tape drive attached to my
33-Mhz 8-MB SCO-SYSV/386-3.2.0 UNIX box for backup and data transfer.
I also have a standard DC300 60 MB cartridge tape drive attached to a
very old SUN-III/160C SUNOS-4.0.3 UNIX box for similar purposes.

Could someone explain the differences between each of the QIC-nn tape
formats -- and possibly suggest an appropriate format to support data
interchange between as many systems as possible?  Is there a lowest
common denominator format which can be read by most operating systems
and cartridge tape drives?

Thanks, AJ Annala