U.S, Korea, Japan and all other countries that are highly industrial and welcomes cryptocurrencies Would be ok.
Japan has the highest Bitcoin taxes by a mile, the US has the silliest having to log every single trade or bit of Amazon tat bought for tax purposes.
At this stage it's more about saving tax than usage. Usage everywhere is pretty sketchy.
The Netherlands has lots of Bitcoin usage, access to SEPA exchanges and capital gains on crypto is tiny, less than 2% I think. And of course Germany has none if you hold for more than a year.