Most of the early boards I called were Renegade, one was WWIV, one was Telegard.
Then I discovered a board running Excelsior! and the rest quickly faded. Inherently multi-line, and supported inter-system links, so I was calling one Excelsior! BBS with 6 lines, and one of them was a dedicated linking line to another board the next city over (still a local call, but itself was local to different folks) with 12 lines, and that was linked to yet another with 8, and everyone could communicate. It was... phenomenally addictive. My grades reflected that.