I'll say:
Yama (Current)
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Kallavan (Current)
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Jinsung ~ Prime White ~ Evankhell (Decompressed + Partial Release)
Current Yama is easily the most impressive to me. He comfortably managed to destroy Proust's Lighthouse barrier, which Robadon failed to do twice (first with his Primal Punch, then with Gran Abuelo alongside Dowon and his army). Yama performed this feat in Base, without using any of his 7 levels of Partial Transformation, any degree of Full Transformation, External Transformation, or named technique. Of course, Proust and Robadon haven't shown everything they have yet, but I doubt they were holding back to this ridiculous extent. This is not even counting Acrinak for Yama. He should be above Regent Tier at his peak.
Kallavan after his power-up managed to one-sidedly dominate the CC Tier Lyborick with only basic attacks, so he's second after Yama to me. I'd put him somewhere between CC Tier and Regent Tier. I'm not convinced he's as strong as Regents yet, although I don't think it's impossible either.
Jinsung, Prime White, and Evankhell come last. IMO, all are around the CC Tier, so the winner would depend more on compatibility than anything else. Jinsung was portrayed as someone who can fight CCs, and was also regarded as a difficult match-up for Slayers in general (most of the ones seen being CC Tier). Prime White fought very well against Kallavan before his power-up (who's CC Tier). Evankhell fared quite well against a weakened Kallavan at the LS, without coming close to using her full power (no Decompression and no multiple Orbs).
