The Sun is reporting that it will be Calvin Ball. Dave Keelan is speculating that Greg Fox might get to decide between (what he sees as) two competing factions among the Democratic Majority.
I have no clue who will be the next chair person. I would not rule out any of them (besides Mr. Fox, the lone Republican). Unlike Mr. Keelan, I would expect that the four Democrats will be intelligent enough to agree on a leadership arrangement among themselves before making their vote public. One solution would be to agree to rotate the Chair among the four Democrats on a yearly basis, since there are four Democrats and four years in their terms. If you forced me to bet, this would be my guess.
Knowing the way Council members elect Sigaty and Watson conducted themselves on the School Board, i.e. in a collegial and cooperative manner and from being familiar enough with the personalities of the other two Democratic members, I would be very surprised to see the Democrats on the Council split on a regular basis.
Who would make the best Chair? Let's just say that all four of them would be good Chair people.