For one, there is no exact science for how Vaylin/Outlander compare to Revan. There is no direct or explicit line of scaling that puts one over the other. HOWEVER, we can look at the Outlander's progression throughout KOTFE and roughly approximate it to how Revan compared to SoR HoT.
We see in KOTFE Chapter 8 that the Outlander, who at this point is at least as or more powerful than the Outlander in SoR, was utterly outclassed by Arcann. Not only does Arcann repeatedly TK and overwhelm the Outlander in the fight itself, but even when the Outlander draws upon power beyond the limits of his body/midichlorians via Valkorion (So much so that after wielding it he is hospitalized for 2 days and nearly dies), Arcann is able to block the energy for nearly a minute and tank the subsequent explosion of energy and fall with little to no damage.
I think this alone shows a rather huge gap between the likes of KOTFE Arcann and, say, SoR HoT. Once we start getting into the KotET gaps though, like when we have Chained Vaylin stomping an Outlander who was > Arcann, Semi-Unchained Vaylin unleashing energies capable of "blasting" KotET Chapter 7 Outlander "into ash," only to have Outlander surpass Unchained Vaylin, etc. Like I said, there is no concrete way to put peak Outlander/Vaylin above Revan, but it's hard to see the argument for Revan when the most we really have is him stomping SoR HoT, something the likes of KOTFE Arcann could arguably do.
__________________ ”You presume limits to my power. There are none.”
If the Outlander is indeed above Unchained Vaylin, he should win. However, the whole Outlander/Vaylin/Arcann dynamic seems like the whole Savage stomped the Count, Maul stomped Savage, Kenobi beat Maul/Savage combined, Dooku stomped Kenobi situation. You sure there is no extra context to them?
There really is no added context. The only confounding variable is Valkorion and his amping of the Outlander”s power/potential. It seems the Outlander”s growth throughout KotET due to Valkorion”s interference actually surpasses the growth of Vaylin, because we see that Chained Vaylin is able to dominate Outlander earlier in KotET, yet in Chapter 8 Outlander tanks Unchained Vaylin”s final attack and guts her, and in Chapter 9 the Outlander’s spirit defeats Vaylin”s spirit.
I basically just take it as Valkorion rapidly increasing the Outlander”s abilities to make him the most powerful vessel in the galaxy, as he more or less says in Chapter
__________________ ”You presume limits to my power. There are none.”
I still have not seen a convincing argument for why Revan is above the Outlander. Ant has argued the strongest line of scaling in Revan's favor, but I don't even think he would say there's a definitive argument for him. It comes down to the fact that the likes of Vaylin (and thus Outlander) have longer demonstrated lines of scaling above SoR HoT (or Ziostiate, if you go that route).
__________________ ”You presume limits to my power. There are none.”
If Vitiate sharing a semblance of comparability to Valkorion is the deciding factor, I assume you”re going with the idea that SoR Revan is on par with or above SWTOR Vitiate. If that ISN”T the case, though, then it’s not really a deciding factor, as we could have something like Valkorion >/>> SWTOR Vitiate >/~ Outlander >/~ Revan or some such shenanigans.
Hell, it”s even possible we could say (peak) Outlander is “comparable” to Valkorion in the same way Vitiate and Revan are, as I don”t really think it’s clear that Valkorion can effortlessly destroy the Outlander.
__________________ ”You presume limits to my power. There are none.”