Crocodile was a warlord but was robbed of feats at the time of the story we didn't know what haki even was if so then luffy wouldn't have had to use water or blood to beat him. Same with ace he was also robbed of Haki feats as well because the plot didn't have haki introduced at the time
that's a lie.
Nope, none of them deserves that title if we talk about power terms, the warlords are used more about their influence and political power and not actually as strong individuals strong enough to counter very strong fighters, the sichi title got pretty much nerfed and that's why oda decided to change it making every sichi these days at least strong enough to survive in NW, removing ppl who were in croc and moria's level (except for buggy who is there for gag purposes).
None? Not even Mihawk, Kuma and Doffy?