Just one: the UK. It wouldn’t make any difference for your taxes, but it would probably make the filing/accounting a bit more complex.
That’s not specific for Estonia, it would be the same with any other country which the UK has signed a tax treaty with. In the absence of a tax treaty, you might have to pay taxes to both countries. You can’t avoid the UK taxes by incorporating︀ in another country, unless you spend a ton of money on local staff and can︁ prove that no work is done in the UK.
If it’s easier for your clients to deal with an EU company, so you can︅ make more money, or if you want to prepare for then it may be worth︆ the additional hassle. Otherwise probably not.
Banking and access to payment processors like PayPal or︇ Stripe is also typically more difficult when you’re not a resident in the country where︈ your company is incorporated.
