Yes i am looking for that WOW factor!Obviously there are a lot of possibilities.
What popped into my head for that size tank would give it good variety of color would be:
10 various colored male guppies
1 blue gourami
3 kuhli loaches for the bottom
I guess my question would be are you going for variety of color (which this tank could do) or a "Wow those are cool *** fish factor?"
If you want to make the colors stand out more, follow the color wheel and use complimentary colors;
Red-Green
Blue-Orange
Yellow-Purple" Do you mean that these color combinations look best together???