So far:
Merc / Mclaren / Williams using a tight, centerline cooling concept. Aston Martin in a totally different direction, but if the rumor of Dan Fallows (I give 5% credibility to rumors) isn't happy, that provide some clues.
Ferrari / Haas / Alfa Romeo, not nearly as tight as packaging. Big side pods with varying degrees of undercut. Maybe Ferrari trusts how much their PU is making now and can go with what I am imaging is a much draggier concept. Or maybe they are struggling some with cooling.
AT and RBR, based on the spy photos, look to be using a concept like Merc / Mclaren / Williams. That would suggest like Merc, Honda has been able to shrink the packaging and work on cooling efficiency.
Renault is the real wild card.