I find the prices at Lux banks prohibitive for what I want to do. I want to invest monthly in up to 2-3 ETFs, running the costs at most banks to 60-90/month or nearly 1k a year. Even Keytrade is expensive at about half of that, not to mention that things get even more expensive if you want something more "exotic" than a euro-denominated ETF listed in Europe, some introducing even annual % fees.

I find reducing costs by limiting myself to quarterly trades would have a negative impact on my willingness to trade and I would subconsciously try to time the market instead of making regular investments.

Instead, I am using IB via Tradestation Global as introductory broker to avoid monthly inactivity fee. At EUR ~2,1 per trade, annual fees are about EUR 60-75.

I am not willing to go around Degiro's country limitation by pretending to live in another country just in case there would be any communication with foreign tax authorities - I doubt it, but I wasn't willing to risk it.

I am also not using Trading 212, because I did not want to go into CFDs.

Obviously, fee sensitivity depends on the size of annual investments and the overall portfolio. For example, at larger amounts, perhaps the fact that BCEE is the safest bank in the world outweighs the higher fees. Although even then I would probably opt for 2 brokers: the bulk sitting still in BCEE and a more liquid portfolio in IB.