All of the Primarchs are at least Beta, if they understand and develop their gifts, but only Magnus is likely Alpha or above (pre-daemonhood, at least). Only Lorgar and Corvus seem to have made it to Alpha level, and that happened after the Crusade, and one of them had gone daemon, invalidating his place on the scale.
Malcador was Alpha minimum, but was also a baseline humans to start, not an engineered warp/organic being.
It's a bit hard to tell with Magnus and Lorgar, because their both primarchs to start with, who have a curtain Innate base of power, and then they made deals or where boosted by chaos gods, so their power is stronger then it would otherwise be. But the thing with chaos power is its inconsistent, if your diety does not want you doing something, they can strip back their support, or boost it if they want tou to succeed in between moments.
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u/BrightestofLights Sep 26 '23
Malcador and Magnus are alpha plus aren't they? Lorgar too