Ragnarok wins handily for me. I'll go through the list in the OP for fun.
Best Hero - Thor. Hemsworth shows more range and really embodies the role at this point. Thor also goes through more on his journey.
Best Villain - Hela is much better than Orm, mainly due to that Blanchett is amazing.
Best Action - Ragnarok has more memorable action to me, well tied to character work, and with Thor vs Hulk being the best high superpower duel yet. Aquaman does have scale on Ragnarok in the final battle though and really good action overall.
Best Comedy - Waititi is a lot funnier and more unique than Wan in this regard.
Best Visuals - Both are very fantastical and imaginative, so it could be a tie. The strong Kirby influences is my favorite thing in the two films though.
Best Score - Ragnarok has one of the most memorable superhero scores as Mothersbaugh did something unique with the strong 80s influences mixed with a more traditional score. The use of The Immigrant Song is also a big standout.
Best Scene - Hard to pick a favorite out of both films, but probably the battle of the Rainbow Bridge, culminating with Surtur.
Best Supporting Cast/Characters - It's very tough to compete with the trio of Loki, Hulk and Valkyrie alone. Then there's The Grandmaster, Korg, etc.
This became pretty one-sided but I do like Aquaman as well. I just don't place it in the highest tier of superhero movies like I do with Ragnarok.