Well, the problem I have with this is that anything labeled as the "Ultimate Guide", tends to be anything but that, with my experience being that guides like this end up reading as a bunch of old tosh.
I can't speak for beers from the UK, or indeed other countries represented, but the US breweries in the Ultimate Guide are your classic old school brewing companies. There are literally hundreds of smaller breweries in the US (most of them unknown in the UK) producing stellar, innovative, exciting beers, while maintaining respect for more established beer styles with a healthy nod towards cask ales.
But then, American Express is about as corporate as it gets, so it's no wonder that their Ultimate Guide features Sierra Nevada, Boston Brewing Co, Odell's et al. But then, it's all subjective.
Regarding David's "...it shouldn't be surprising that British brewers are on there, brewing beer as good as, if not better than, modern American brewers...", which "modern" American brewers are you referring to? There's always been a bit of an anti-American backlash on these pages, mainly - it seems - due to unfounded comments that American IPAs are trying to take over the world.
The "modern" US breweries are anything but that, which I've described three paragraphs up. We recently went to a 10th Anniversary party in San Diego at Hamilton's Tavern, which featured a tap takeover from the aptly named Modern Times Brewing Co. They had 30 taps featuring Brown Ales, Stouts, Sours, a Gose, a couple of Porters and a fine selection of barrel-aged beers, with four cask beers. IPAs? Just the one IPA on tap, out of 30. That's entirely typical of what you can expect of "modern" American brewers.
I'm not claiming these brewers are better than anyone else, but David, I do think you serve them an injustice. One of the reasons I stopped contributing to these pages is that I finally came to the conclusion that the beers I drink have no place on these pages.
And the "Ultimate Guide" doesn't help either!