Coincidental reasons why the PT brigade is so strong
I'm not making direct arguments in support of any era's characters, nor am I analyzing forum social dynamics (which also play a huge role), but rather I'm talking about ways that Legends has been configured which favors the later eras for perhaps unintended reasons. This, again, isn't a direct argument for or against the arguments' legitimacy.
Backwards compatible accolades: An accolade calling Sidious the most powerful Sith of all time can transfer backwards, while one saying that about Vitiate wouldn't apply forwards to Sidious unless if it actually references the future, which almost never happens.
More Jedi / Sith parity: Whereas ancient-era stories often focus on an ancient sith who is so far beyond everyone else at the time, the PT-era features Sidious, who has multiple "most powerful Sith ever" accolades but also has several competitors such as Yoda and Anakin. This drags up the Jedi and Sith around Sidious whereas someone like Exar Kun is weaker than Sidious and yet has less competition, perhaps because the story is centered around him whereas the film-era isn't just about Palpatine.
More sources + a forum preference for high-balling: Modern eras have a lot more published material, which means that you'd expect to get more high-end feats for characters. You might expect more low-end ones as well, but the forum tends to focus on the higher-end ones, which I think is justifiable for reasons I won't get into here.
More text-based sources + better prose writers: Most of the best feats in Legends come from novels and sourcebooks where demonstrations of power that would be difficult to sell visually like singularity manipulation can be acceptably described. The PT-era has more of these, along with better prose writers like Stover and Luceno.
Reverse scaling from Sidious vs. Valkorion: since many like myself put Palpatine above Valkorion, we must also put people like Exar Kun far lower relative to Sidious than what the forum used to generally do.
Thoughts?