What color primer to use?

So I'm about to begin painting for the first time, but I'm not sure what colors to buy. I play Star Wars Legion so I'll be painting a bunch of stormtroopers, death troopers, and other very monocolor minis. Should I use black and white primers for them? Or do neutral grey and paint the colors?

Bonus points if anyone can tell me if wildspire minis are good for a first time project.