I avoid connecting through Heathrow when I can. Horrible, crowded airport. And the taxes on frequent flier tickets are outrageous. Using AA miles the taxes are at least $100 more than say straight to Paris. That’s on AA flights. On BA flights taxes are $600, making it not even worth it use miles.
I'm not crazy about any of the big airports these days... anywhere. When I lived in L.A. I used Burbank instead of LAX whenever possible, and now I try to use Palm Beach instead of Fort Lauderdale or Miami.