My 3 favourite alien races...
-Dathomiri / Zabrak, charecters such as Darth Maul, Savage Opress, Mother Talzin from the Night sisters.
-Togruta, the female charecters such as Ahsoka Tano, Shaak-Ti.
-Twi'leks, the female charecters such as Darth Talon, Aayla Secura, Slave dancers from ROTJ.
Mainlly just really like visual look to these charecters, the colours used look great, and the females look HOT.