VIZ.
Kotoamatsukami makes a good point, if that is viz then we can consider it to be more credible, but MP translated it simply as one of. Viz obviously takes priority. But the first doesn't necessarily mean the strongest either, it can be just an order of who got put on the list first. Or just o way of numbering arbitrarily. Show me the scan from Chapter 490 page one where it says ichigo is a SWP, also show the scan where aizen is shown to be an swp. Do they get different numbers. If not this is probably meaningless.
Ofc, VIZ is most credibile translation, but it don't need to mean it's always the best.
But not just VIZ but mostly of Asylum translation agree with the sentence, one of them work for Manga Stream. Plus, two translators (BadKarma and Cnet from MangaHelpers) who are one of the best on net have same translations.
This is BadKarma.
Page 16
Juhabach:特記戦力の1
Special Asset Number 1
Juhabach:更木剣八
Zaraki Kenpachi
This is Cnet.
16
Leader: Notable Threat Number 1... // Zaraki Kenpachi. // How the mighty... / ...have fallen. // Pathetic.
I never intented to make point that Zaraki is stronger than Aizen. Because I think it's evident that Current Aizen is far above Zaraki. But my point is that Yhwach see Zaraki as bigger threat than Aizen.
Also, I would left room for Zaraki power up like removing patch and achiving bankai. Maybe at full power he could be stronger than
Zaraki Aizen, but I sure don't think he is currently stronger. My point again was just to show how Yhwach see Aizen and how he see Zaraki.