What country, regardless of language, is most like America?
In geographical terms probably Canada.
In judicial terms (retribution rather than rehabilitation- use of unusual & cruel punishments & death penality) ;- Saudi Arabia.
In democratic representation the USA stands alone among the 30+ OECD nations and probably the best comparison when all factors of good governance, corruption, democratic principles et cetera are seriously considered is the technically still developing federal republic of India.
In cultural reach terms and influence on world media and popular entertainment the nearest comparison is the United Kingdom of Great Britain & Northern Ireland.
In economic terms the comparative is The people'd Republic of China.
In military terms the comparative is The Russian Federation.
In terms of social care, health care and benefits for citizens the nearest comparative is Singapur.
In terms of religious observance and prevalence and influence of marginal or fringe relgious sects on general life-
The closest equivalents are Israel and Iran.
I put a lot of thought into each category and am prepared to justify each opinion if pushed to do so.
I mean no offence ro any US American who might read my words and see them readily compared to :-
Canada, Saudi Arabia, India, Singaore, UK, Russia, Israel and Iran.
I hope my answer is helpful and thought provoking.
It depends on what aspects you're comparing. Based on my observation and conversations with folks from lots of countries I offer the following:
Canada is the most similar in accent, they're aboot as close as you can get to sounding like an American dialect. Their culture is a kinder/gentler version of our own and we share similar pop culture memories (tv signals crossing the border easily - "Let's build a faraday cage to stop illegal signal migration across our borders!") at least in the last few generations.
However, Australia is very similar in terms of having a similar "Wild West" period in history and there's a reverence for "rugged individualism" that marks both countries. New Zealand would be like Australia's Canada, close but not quite the same.
After that the differences in cultures puts most other countries off the list.
If you're asking about climate or topography, I've clearly blown it.