How do you treat "Variant Covers" in your collection?

I'm largely a DC collector and just about every comic published by them has 2-3 covers minimum.

• Do you count the variants as your "I'll buy whichever one I like and call it done?"

• Do you need to have the "A cover" since that's the regular one?

• Do you have runs where you ONLY have variants and no A covers? or

• Do you collect them all to be a completist?