Rear naked choke, learned it while training Bando in the early 80s. The first submission learned in a BJJ class was probably the arm bar from mount, which I learned in the late 90s. It seemed like it was the only submission we used to work on, we'd do reps of it almost every class like a warm-up drill.
My go to submission is the Darce, which I go for all the time and never hit. It's like I have submission turretts, I don't have long arms and never set it up right, but I can't stop going for it.