Boeing 737 vs. Airbus A320 advantages

[Diamondpilot]

Hi all,

If you were a boeing 737 salesman, how would you sell the Boeing 737-800 in comparison to the A320? So in other words, what are the unique selling points (USP's) of a Boeing 737-800?

I've never flown a real jet btw, I was just wondering why a company would choose a boeing 737-800 over a Airbus A320..

Thanks!