I suppose the best coffee is actually provided on the only true legacy carriers left in this country, 5T/7F on YOW/YUL-YFB. The free coffee and Bailey's after dinner is great! Otherwise I think their coffee is the worst of all the carriers I fly regularly.
For those wine lovers up thread, the free wine with dinner is also a great touch. Of course for ~$3k return in Y for an under three hour flight it should be.