I still to this day have not seen a yonko being on Issho's level, fujitora is underwhelming and I cannot see any yonko losing to him or him stalemating one. Oda didnt outright say they are equal. Then why would he say kaido is the strongest. We both acknowledge that the two groups are top tier. At this point we are looking for the slimmest of margins and in that the edge is yonko. WB at a younger age, Kaido and now even BM are getting incredible hype, something I cant say for the admirals bar Garp but not current admirals. I just dont see fujitora or kizaru at that level of hype especially fujitora. Again Im not saying admirals are bums I am saying they seem to be slight step below the average yonko.
Fleet admiral did get a slight edge here, but based on the info we know already we know that garp> sengoku. But maybe that is a special case since he rejected every promotion that came to him.