Few of us will have had the chance to sample a full range of dishes of all of those countries within those countries. Only those who have can give a meaningful answer. Seems to me like it's more a question about which restaurants and cooks' styles have we most enjoyed.

And Chinese food in the UK is different from Chinese food in Spain which is different again from Chinese food in Japan. Then again, much of the 'Indian' food eaten in the UK might be Bangladeshi or Pakistani. And I have no idea if any of the Malaysian dishes I've eaten at places that serve Malay and Chinese food is actually Nyonya.

Personally, I've had excellent Chinese, Indian and Malay dishes. I've also had some rather horrid or mediocre ones. When I consider the percentage of good/enjoyable and bad/unenjoyable foods within any of these categories, there was a higher proportion of Malay dishes that were enjoyable.
To me that just means that there are many more 'Indian' and Chinese restaurants and a local population familiar with their cuisine yet willing to accept low standards to support them. As people in London are not so familiar with Malay food, perhaps the chefs need to try a little harder to get custom, as well as being free from the locals' misguided expectations of what the cuisine should be.

Usually I'll prefer whichever food is being prepared by the best cook with the best/freshest ingredients.