alt Hacker NewsRaw economy size can be misleading in two ways. The value of a dollar is much less or much more depending on where you're at. So an economy of 10 shekels might mean an economy of 100 widgets, or it might mean an economy of 1 widget. Purchasing power parity (PPP) attempts to account for that. The second is that economies are largely a product of population. An economy of a million making a million shekels is quite a bit different than an economy of 10 making a million shekels, so you also want to look at per capita values. Even both of these adjustments combined [1] can be extremely misleading (see: Ireland and many other places...), but they provide at least a less unreasonable basis for comparison than nominal dollars. And the UK is currently 30th there.
[1] - https://en.wikipedia.org/wiki/List_of_countries_by_GDP_(PPP)...
I think GDP per capita can also be misleading though - the GDP per capita of Luxembourg or Brunei is high, but they're such small countries that it's kind of irrelevant.
Setting aside the special cases (tiny, oil money, weird finance sectors, tax havens etc) there's basically a handful of countries which are clearly doing something right - the US, Taiwan, the north-eastern European countries (Germany, Austria, Netherlands, Belgium, Denmark, Sweden). Most of the other "developed countries" are sitting in the same sort of GDP per capita range of $65-$75k. Ranking these isn't so meaningful - the difference between the UK and France is only 1.5%.