It might be a bit controversial notion. But when I try to look for extensions say for completion framework there are many available and I used ido and then moved to ivy. I knew helm existed and is much more powerful in terms of feature-set, but never used it.
I read that emacs can report on keyboard usage (I think from xahlee’s posts). Can it be repurposed to monitor which extensions are used often in users setup and they can share that report if they wish to public say via melpa like services. I suppose that melpa downloads can be used as a measure of usage.
Instead of wondering about what everyone else is using, why not try each one and see what works for you? Ultimately, that’s all that matters.