Vindicta and Paradox are my two most played and highest priority, followed by Wraith, Infernus and Warden. Last night I tried Grey Talon for the first time and found him quite fun as well, so he'll probably be my third pick from now on. Some.of the upcoming heroes look quite fun and interesting so I might enjoy some of them too once they're released.
Calico - I like cats and currently playing as her just feels right.
Ivy - I really like her combo and sitting on people.
McGuiness - Her turrets are cool and often ignored (especially if there's lot's going on) which can be a really bad move. Reminds me of playing Engineer in DRG and her ult gives me the same feeling as firing artillery in Factorio.
I played a lot of McGuiness before I played ranked, after that the way I pay her doesn’t mesh with the meta so I switched but it was a lot of fun before then for sure. Will have to try calico in the test mode!