One could use many different metrics for comparing research output in different countries. My own preference is for averages (either in the number of papers or number of citations); a fancier version would perhaps normalize these averages using some relevant measure (GDP, per capita GDP, population, science spending). At the other end of the comparison spectrum, we have studies using the (rather small) number of Nobel winners.
A recent study by Université Catholique de Louvain researchers uses the number of Highly Cited Researchers as a criterion for ranking countries. It comes to some interesting conclusions, including one about the importance of English.
We show that the English proficiency effect is fairly strong. For example, if France were to improve its English proficiency by 10%, thus reaching the level of the Netherlands, the number of French HCRs would increase in the long run by 25%. However, besides their linguistic advantage, former UK colonies also display a higher efficiency in producing HCRs. For example, Australia, Canada, Ireland, Israel, New Zealand, Singapore, the UK and the US have, ceteris paribus, 76% more HCRs than other countries. In order to match such an advantage, EU countries should more than double their research budget, or more than triplicate their human capital stock, or increase their per capita GDP by around 40%. These numbers give an idea of the strength of the UK legacy or, maybe, of the choice of US-like academic institutions made in those countries. In any case, they suggest that a variable directly related to the quality of the design of academic institutions matters more than the R&D budget, the GDP level and human capital.