Wano has all of these except for the admirals (technically did appear in between the acts but you know what I mean)
MF Arc was the meeting place of so many Major Side-Characters that we met before, not New
It's an Arc where we see Aokiji, Kizaru, Sengoku, Garp, Smoker, Koby, Whitebeard, Mihawk, Hancock, Doflamingo, Kuma, Moria, Ace, Crocodile, Buggy, Blackbeard, Shanks ... etc & the new Characters were also very interesting such as Akainu, Jinbe & Ivankov.
Each of these Characters can have their own Arcs & they can appear multiple times & they are important on their own
Please don't compare it to Wano Raid, where most Characters are Newly Introduced & only exist for the sake of this Arc & nothing more.
Only returning Characters are Supernova & Big Mom