I speak Marathi, but haven't ever lived in Maharashtra. In Hindi, it wasn't uncommon to hear "ek number ka ...", but to me the context was always a negging directed at the audacity of the joker, and never as a rating of the joke itself. I also haven't heard anybody use "ek number .." in Hindi in any form in a very long time. It's possible the phrase evolved different contexts and implications in the two languages.
I was born and brought up in Mumbai, Maharashtra and Marathi is my native language.
Ek number was commonly used in my childhood days in Mumbai and it means "First class" or "Classic". Typical uses: ek number joke, ek number daaru (daaru = alcohol, liquor), ek number maal (First class, good looking, hot girl), ek number vada pav (classic food dish) etc.
I speak Marathi as well as Hindi and probably use that term daily just like what that article mentioned. AFAICT most of my friends and family also use that term frequently. Example usage could be “ek number Bhau...” when complimenting some post on WhatsApp
