If one wants to judge 'best' on 'producing academic high achievers', something some of us would want to take issue with, then you can very easily find the data at
http://www.pisa.oecd.org" onclick="window.open(this.href);return false;, which will give you all the international world rankings based on testing of 15 year olds. If you then cross refer to
http://www.unicef.org" onclick="window.open(this.href);return false; and search on their international study of child happiness, you might start to contextualise some of the figures.
Crudely, countries like Korea, China, Vietnam and Finland usually top these tables. If you try to isolate the factors which seem to lead to high academic achievement across the board they tend, very very crudely, I do stress, to come down to:
No early selection ('tracking' as it is generally called) ie mixed ability teaching, often in whole class groups, and in Asia, in a way which many here would find quite didactic - instruction and little attention to individual 'needs';
No early specialistation, ie opting out of subjects;
A very 'equal' society without a well established class structure;
Parental support for learning...in Asia this tends to be a big driver, and in Finland there are complex implicit social reasons for it;
A centralised education system without lots of regional variation and little devolving of power to individual schools;
Size- with the exception of China and Japan, countries doing really well tend to be small and not have enormous numbers of schools;
Wealth - though the big exception is the USA which is very rich but also very diverse economically, and very devolved in that states run their own education systems.
There are other things like teacher training and the level of qualifications required of teachers. The value put on teachers and their standing in society tends to be higher in these countries. And another factor is focus of teaching - for example in the UK we have a very curriculum based view of teaching (
what to teach) whereas many other countries focus on
how to teach, the pedagogy rather than the content. On the whole those countries have higher academic achievements than our own. But this is a whole essay
No easy answers, in short.
HTH