I hate, absolutely HATE pdfs ... trying to open them on a Mac is next to impossible as Adobe acrobat takkkkkkkkkkkkkkkkkkkkkkeeeeeeeeeeeeeeeessssssssssssss soooooooooooooooooooo damn long!

@alexandra PDFGear is a pretty good one for Mac. iOS/iPadOS versions also available.

One of the best things SteveJobs did was push Apple away from using AdobeFlash, which has since vanished.
Im not sure about pdf as a format, difficult to edit, but its frequently used even though there are word or opensource alternatives