Here's what I look for in a bee:

Bright, clean yellow. I don't care for "dirty bees" that have lots of speckling or browning out.

Crisp, reduced pattern. The reduced pattern is really optional, but I like for it to be mostly connected, with few if any stray dots or lines.

High white sides are a plus, but also not necessary. Some people prefer the low whites.

Really if you go for bright color and a clean pattern you should be good to go.