I currently have an in-person group of 4 + me (DM) and a remote group of 3 + me (DM).
I really like 5 good players best, but 4 works just as well. Six is too many and three is fine, but always feels like it needs one or two more opinions in the mix to have the right texture of gameplay.
One table is five people (which will be 4 players), several who rotate as DM for a campaign at a time though may alternate weeks for different campaigns, and the DM usually adds in one, two, or rarly three people. For example the CoS campaign we just finished had 7 players + DM near the end, but 5 or 6 is more common.
One table is five players + DM.
I picked 5 in the poll, it seemed a reasonable approximation for both (integer) median and mean looking at the last 18 months of play.
I have 9 players in my campaign. However, it is rare that we have more than six at the table - so that is what I chose. I have players that drive from a long distance away and just cannot come every week.