all these brokers operate in spain. check if they offer pamm accounts.
you pay a capital gain tax of 21% in spain and thats pretty much the average of the EU. so no benefits and no downsides of taxation.
profit up to 6000 = 21% tax
profit from 6001 up to 24000 = 25%
profit 24001up to infinity = 27%
if you open a investment vehicle to trade on the behalf of (LLC for example) tax is between 25 and 30%.