Katakuri is a great character for the limited amount of build-up he received, and being showcased to go through his own character arc within the 15ish chapters him and Luffy fought. It was a bold move on Oda's part to take what would be an otherwise secondary villain in any other other arc, and be able to successfully turn him into the biggest threat to Luffy, in an arc where there is a Yonko. It worked though, and his character elevated dramatically because of it.
Crocodile on the other hand had way more build-up, and was much more fleshed out from the beginning. He's arguably one of the best written villain in the series.