"Late Roman Cataphracts: Draco or Vexillum?" Topic

I was hoping someone could help me out here. I'm painting up a 12 model unit of Western Late Roman cataphracts and I am trying to figure out which standard to use.

I was under the impression that pretty much most all Late Roman cavalry used the Draco, especially Samaritan influence on Roman cataphract units.

But a few pictures on the google showed cataphracts with a Vexillum.

I'm curious on which way to go. A vexillum may be interesting to try and paint the portrait of an emperor or archangel, but I am not sure it it would be accurate.

If geography is relevant (i.e. Italian command used vexilla, Gaullic command used dracos, etc.), these are meant to be pretty generic western Roman cataphracts which will be used to augment a Legio Comitatensis for Moesian, Gaullic or British scenarios.

I appreciate any advice and input as always.

My reading on the subject give detachments using the vexillum when operating away from their parent unit.

Using the draco for the mobile army would be a nice way of distinguishing them from border units carrying a vexillum.

All my units have draco standards with the commander having both draco and labarum.

Thank you very much. It sounds like what I need is the draco, then. I have a Limitanei unit with some light cavalry and horse archers, so it's good to also know that they get the vexillum instead. Super, thanks again for clearing it up for me.