I think I built my first forum in 2003, it was based on phpnuke and then i went phpbb. I have used smf, vbulletin and ipb over the years, until 2013 when i converted all of my forums to xenforo. Well, all that keep going anyway.
Started off in 1989 using a software called MajorBBS (a DOS based system), which then morphed into WorldGroup (still a DOS based system), then moved to phpBB, then VB and now to xF within the last month.