The ones generally viewed as most effective as the usual suspects: Nordic countries (all of them), US, UK, Germany, Australia, Canada, and to an extent also Japan.
Then we have the mad ones: Spain, France, Italy, China, India, and probably UAE will be in this group by the looks of it. These are highly unpredictable tax authorities that miss a lot of stuff. But when they catch someone, they don't let go until there's no life left. Tax vampires, as opposed to tax police.