The best lectures I had at uni were some math lectures where the professor had an overhead with a transparency roll. He'd write on the transparency as if it was a blackboard, and could roll up and down as needed to review older equations or make room for new.

Blackboard worked well too, but not as good, since the professor could sit in front of the overhead so things lined up better, and the transparency pens had much better visibility than chalk on a (green) blackboard.

Most other lectures used PowerPoint, due to the professors being forced by the uni administration, but for me a PowerPoint lecture was barely worth the time. The information just wouldn't stick, since the PowerPoint format doesn't lend itself well to writing notes from, and without writing notes I hardly remembered anything.