Victor Vianu Dennis Shasha Paul Kantor Scott T. Leutenegger Alfonso Cardenas Luis Gravano Panos K. Chrysanthis Daniel Barbara Jamie Callan Shlomo Zilberstein 3 or 4 panels. Putting a good panel together with differences of opinion, and strong interaction, is hard.
Most panels become a series of poorly prepared mini-talks.
I would rather devote the same time to a plenary talk. These are often quite useful.