I think she's easily a high herald. She is strong/durable enough that she can hang with Superman(most of the time. I have seen him one-shot backhanded *****-slap her, though, was pretty funny, he was being influenced by Eradicator to think more like a Kryptonian).
In adventures of Superman #498, Maxima is the only one in that incarnation of the Justice League that was able to actually hurt and withstand blows from Doomsday, besides Superman.
And her telekinesis are pretty powerful. When she was weakened and demoralized(Starbreaker had absorbed quite a bit of her energy and the people she ruled kicked her head in), she was capable of manipulating continental plates on a planet that was supposed to be much larger than Earth. During PANIC IN THE SKIES she matched and defeated Brainiac(when he was amped by WarWorld) in a telepathic stand-off. She's also shown a degree of superhuman speeds.
I'd give her roughly a split with Wonder Woman (slight majority to Maxima), Sersi (slight majority to Sersi), Hal Jordan, and X-Man....IDK if you consider Herc with his mace or Current Hulk high heralds, some do, some don't, but I give her a solid majority over either of them. She's not getting a split with the cream of the crop high heralds though (Superman, Silver Surfer and Thor (unless she hit him with his own hammer), who are the big three IMO). But just because you're not splitting with Surfer or Supes doesn't mean you're not a high herald.