Recently I started to see a bit of a pattern with my biases and I thought it's an interesting topic 
For me, most of my biases are:
- short
- in the vocal line
- but also good at dancing
- have a funny personality / good at variety
- can have a dual persona and go from cute to sexy easily
The exceptions are that Soojin is in the dance line and is on the taller side, and Jisoo and Sunny (to some extend) aren't considered good dancers.
My biases are:
Twice's Jihyo ♡ SNSD Sunny ♡ Blackpink's Jisoo ♡ f(x) Luna ♡ Gidle Soojin (ex)
I don't have a clear bias in Red Velvet but I'm leaning towards Seulgi or Wendy, which would prove my theory 
Things like a fun personality or enormous charisma aren’t what make it or break it for me so 
