Michael Jennings has a fascinating post at Samizdata that explains, in part, why I’ve been to Stansted and Gatwick more times than I’ve ever been to Heathrow—and also, in part, why I haven’t set foot in any of those airports (or, for that matter, anywhere else outside North America) in 12 years.
To some extent, the practical problems Michael describes have been reduced by code-sharing and mergers; for example, I could now fly to Britain from Memphis—the relative boonies in American aviation, at least when it comes to "hub" airports—in several dozen different ways, the most convenient of which is probably to take the every-other-day Northwest/KLM flight from Memphis to Amsterdam then any of a number of flights to major British airports via KLMuk from Amsterdam.