United States: quite positive
Americans and Britons have long been friends—perhaps "brothers" is a more appropriate term, as we've shared many a success and conflict. Anyway, whenever the United States seeks support for some international venture, it looks immediately to its motherland for backing, and we like to think the opposite is true as well (as an example, Americans found lacking British support for our toils in Asia and the Middle East quite offensive; we figured that each nation would simply help the other regardless). Trade and international relations are quite strong and healthy between the two, and much culture spills over as well.
There are a few random (and presumably untrue?) stereotypes regarding the British: bad teeth, terrible food, etc., but what's a few laughs between friends
. And, truth be told, Britain is probably the only European country all Americans tolerate; France, Germany, Italy, Spain, etc., each have random stigmas to certain individuals, groups, or nationalities, but everyone's well aware and accepting of the British impact on America.
If I'd ever leave the US (I probably won't, but if I would), it'd be to Great Britain.