This is an update of this post:
Up to 107 games of data now, with each character on about 66 plays, mostly 4 and 5 player games.
After each game the characters get a score, such that first = 1 and last = 0, with the other placings a fraction depending on the number of players.
Here are the average scores for each character:
0.52 Wonder Woman
0.47 Green Lantern
Characters really evening up now. Batman had a good run recently but is still last.
28% Wonder Woman
28% Green Lantern
Aquaman is really consistent but does not win quite as much. Aquaman and Cyborg both come last only 16% of the time. GL comes last 28% of the time - only better than Batman (29%).