Note pounds are not technically accurate, but are pragmatically accurate.
https://en.wikipedia.org/wiki/List_of_ONE_Championship_champions
Strawweight
Current strawweight champ is Joshua Pacio. The entire strawweight division has been a rollercoaster ride, which I made a thread about here:
https://forums.sherdog.com/threads/...cios-first-strawweight-title-defence.3882925/. There have been 6 separate champions in this division, and only once has a champion successfully defended his title. Pacio is expected to make his "first" defence against Hayato Suzuki. Pacio is up there as the world's best strawweight right now with Haruo Ochi, Sunabe, and Kitakada.
Flyweight
Current champ is Adriano Moraes. He's good, and has beaten all of ONE's "old" blood (Geje Eustaqio and Kairat Akhmetov namely), but hasn't fought the new blood: Danny Kingad, Yuya Wakamatsu, Tatsumitsu Wada, or Demetrious Johnson. DJ will crush him, and I doubt he could beat any of those other three guys.
Bantamweight
Longtime champ Bibiano Fernandes lost his title in a close rematch to Kevin Belingon. In the trilogy, Belingon got DQ'ed for throwing a knee to Bibiano's head on the ground. Fourth fight likely next. Neither of these guys would be top 10 in the UFC though.
Featherweight
ONE's long time champ was Marat Gafurov, who was considered to be a blue chip prospect -- until he got KO'ed by Martin Nguyen (current champ), and then KO'ed again by Koyomi Matsushima. Nguyen went on to move up to lightweight to win the 155 title, to become ONE's first two division champ. He then moved down to bantamweight and lost a close decision to Fernandes. Nguyen subsequently vacated the lightweight title, and is only the champ at featherweight right now. Decent fighter, but not top 20 in the world.
Lightweight
Like strawweight, the lightweight divsion has been a rollercoaster ride for ONE. Shinya Aoki recently won back his title, only to lose it in his first defence to Christian Lee. Lee is a decent fighter, but not top 30 in the world.
Welterweight
Askren defended his title three times before coming to UFC. New champ, Kadestam crowned in late 2018. He's overall unimpressive, and would not be competitive in the UFC.
Middleweight/Light heavyweight
Current champ is aung la nsang in both divisions. He's a big fish in a small pond, and since winning the middleweight title in 2017 against Vitaly Bigdash, he's had nothing but overmatched opponents. Not top 20 in the UFC.
Heavyweight
Brandon Vera is the champ in this joke of a division.