For the celestial Warlock, pact of the chain, what is an alternative familiar you would suggest?

For the celestial Warlock, pact of the chain, what is an alternative familiar you would suggest?

I was going to request an imp, and flavor it as an adversarial relationship. Sprite would be fine but I’d like to know any thoughts for a more friendly celestial familiar. A celestial sprite or a celestial pseudodragon are good options.

— Jeremy Crawford (@JeremyECrawford) August 10, 2018