whether she had the highest midichlorian count is like a karate guy arguing that Khabib was a shit fighter because his reverse punches from horse stance were shit.
Midichlorians are an overall "energy potential" rating. Most people are capped off at say a AA Battery, where teh Jedi would be like a golf cart battery. Yoda, Sid & Anakin had a bigger battery than that. (A generator to power a warehouse for example.) Instead of making analogies like this, we can simply use numbers:
- Non-users = 2
- Talsin = 50
- Other Nightsisters = 500
- Maul = 1,000
- Sid = 5,000
I just pulled those figures out of my ass just now to serve as the example, so don't hold me to the numerical differencez. I'm just saying that the Midichlorian count is a method of measurement that puts numbers on force sensitivity thus making it easier to discuss.
Midichlorians are fake and gay
I've never had the problem I see others have with midichlorians. Whatever teh name is though doesn't matter, we can discuss it in terms of "higher & lower force sensitivity" if that works better for you.
Talzin had more force than typical people who are oblivious to it... while having less force sensitivity than even the other night sisters... & obviously less than Maul & Maul less than Sid. That's all I was saying.
Sid picked him as apprentice because as a male Dathomirian, he was a born simp.
Sid picked Maul at 14 years old because of his struggle with anger.... & obviously his sensitivity to teh force was high (midichlorian count n stuff)
Sid visited Talzin's home many times while teh pre-teen Maul would hide in his bedroom from teh ominous guest. Talsin wanted to be Sid's apprentice... & Sid strung her along insisting that she would never be his apprentice unless she givez him her 14 year old son. EEK!!! ...then he never made her his apprentice anywayz... lol

Sith gonna sith.
Talzin made the most of her game and in terms of OP abilities, no one in SW canon comes close other than Sidious. I'm not sure if even Sidious could voodoo people, possess others, conjure dead spirits, heal crippling physical and mental damage, create weapons and objects out of raw energy, block force lightning without a lightsaber, etc. When Sidious defeated Talzin, he had the assistance of both Dooku and Grievous. Single combat on Dathomir, Talzin vs. Palps, I think it's too close to call. But that would never happen because Sid doesn't fight one on one without backup on deck.
She definitely did make teh most of her inherent ability & attachment to Dathomir.
Her power in teh force may not had been as high, but she knew how to channel & direct teh "Ichor" (Green mist energy of Dathomir) through her... better than any of them. The higher end stuff Talsin did, could only be achieved on Dathomir... or if she had a mobile container to travel with, that she could draw upon for power. (In her fight with Windu... she lost the fight when her portable power container broke.)
Those with more force sensitivities could do their mystical stuff anywhere... & without a physical "power container."
Conversely, Talzin... while on Dathomir... could project teh green mist power (Ichor) to manipulate people on other planets, but teh power was not as strong as compared to if teh person were on Dathomir.
What made Sid more OP was his political ruthlessness, big picture thinking and narcissistic paranoia. It would be like the president of the U.S. receiving daily classified intel briefings, knowing everything going on in the world but also being manipulative, telepathic, telekinetic and on the short list of GOAT hand-to-hand combatants in the galaxy. All of that combined is what made Palps the GOAT movie villain.
For sure Sid's political & strategic forward thinking would've brought him to power with or without his higher force sensitivity.
That said... what better tool to negotiate politics... than to be able to read someone'z mind~ To manipulate someone's mind~ and also to become the separatists leader through brute showing of force as Sidious thus being able to orchestrate teh war in teh prequelz by being teh leader of both politics & brute force. He used all his abilities to make that happen. It wasn't all politics.
This discussion remindz me of teh new Ahsoka with Sabine being a capable warrior, but hasn't yet tapped into her force sensitivity. She'll never be as capable as Ahsoka, but she can train to become more capable than she currently is... & maybe that givez her an edge over others who don't do such thingz.
By contrast Talzin was extremely powerful while on Dathomir, but needed Sid to awaken her force sensibilities so that she could better operate in any location.