It depends. It seems many people take that if you decide to say "founder" you are believing yourself above the rest. Not everyone who has the same tag did it for the same reason.
I can see it to be silly to call yourself "Founder" or call the other "Co-Admins" and I used to think they were being show off too. Then I saw some retired admins who were actually the founder and stayed as a normal member. I think it was fair they had the name and distinction if they started the community and helped it grow, even if they moved on the project. I stopped seeing it as something that separate people.
As other people have pointed out it also depends on the software you are running your forum into. I find it useful in places like Forumotion, where only the founder can do certain things, it helps to know which of them is the founder. Better than searching for /u1 (the first member to register), specially when they leave that first account as an impersonal account (news/emergency/etc).
At the moment in my boards I am not using ranks, as it is the groups what determines colour and 'permissions', so instead I am using manually the images in the mini profiles. This allow me multiple images at the same time. I am seeing it as a way to convey some information quicker.
In colour and rank, I always call us staff. I respect my team members and appreciate what they do for the community, and we are not to board about our position but to help around being friendly and polite. We're all still members.