It depends on what you're trying to do, as their functions are not analogous.
MB128 - not terribly useful, as a game must be programmed to be able to save to it directly and not that many can; and all the games that include MB128 support are cd titles, so it's just a paperweight if you only have a PCE base system. Assuming you do have a CD add-on or Duo, you can use it with one of the games that has a memory manager utility built in to backup and restore the system's save ram into one of 64 slots, much like you can with the Tennokoe Bank card.
Tennokoe Bank - useful for backup and restoration of the system's save ram into one of 4 slots. Same as the MB128, it's the entire contents in one step with no provision for moving individual files.
Backup Booster 2 - only useful if you have a bare system and want to add save capabilities. Like the ram built into CD systems, there's just one slot, so you'd still need one of the other two if you want to backup your saves.