Interesting one. Not having lived in England now for most of my life (although I go there regularly, to see my blue lads), I have a huge distance from the country I grew up in. It would be easier to say “Things I like about England” (you notice I'm not saying Britain, which has now become quite a loose polity, I think — maybe it always was):
Most particularly, a good pub, usually out in the countryside, out on the moors, maybe. Maybe with a fire going in winter. Good ale, maybe some decent food. No screaming kids. A beaten up, tatty settee here and there, over in a corner. A place where the locals stare at you a bit. That's ok, that's normal. You're not from round there.
Secondly, without question, the English (British?) sense of humour, and specifically, banter. Banter with a complete stranger, a ticket inspector, a shop assistant, someone who asks you for directions in the street. It'll last for twenty, thirty seconds, a minute at the most. You'll never see them again. That's not the point.
I'd say that those two things are things I've found nowhere else on earth. Many, many other good things, but not those. Not in concentrated form.
I could add — the English language. The English one. Not the Americanised version of it which has crept in over the last forty years and made itself so thoroughly at home, especially among the young. The one that's full of idioms and expressions and weird words that, whenever I use them with an American friend (I do have them!), they just gawp at me.
Brexit? Best to keep my mouth shut. I've said, right from the start, that's it you people's business. I know one thing, and it's incontrovertible. Half of you voted for it. Half voted against. (And a dismayingly significant number of people didn't turn out at all). That — in itself — is a mess.