British Airways doesn’t have a very good business class. It’s terribly expensive when redeeming miles thanks to choke-worthy fuel surcharges which continue even in an era of $45 oil. For transatlantic flying to and from the U.S. both American Airlines and Virgin Atlantic are better. I’m not a fan of Delta’s 767s, but DeltaOne is probably better than British Airways business class.
However it makes sense to buy British Airways when it’s super cheap.