Kitana and/or Kung Lao. But I am extremely happy with the current lineup (with, of course, a few exceptions).

You beat me to the petition homme!

Blaze cause his comeback in MKDA gave him the opportunity to have a cool role in MKD
Khaemeleon as a Reptile's friend/avenger
Kung Lao cause he's amazing
Rain cause he has great powers and is related to Edenians (Sindel, Tanya, Kitana, Jade...)
Sektor with the Tekunin, and cause he's the best cyborg
Shao Khan as playable and depowered from his previous appearances