What platform are you using to trade ETF's?

Hi all,
Very general question regarding ETF trading...I would be keen to hear what platforms people are using. At the moment I have a Degiro account which I use for small-scale share trading. I am thinking of making a much larger investment in a basket of ETF's, holding them for medium to long term. I know Degiro is just the broker and the ETF's would sit in an independent holding company in my own name, but I have an irrational fear of investing big money through a platform/organization that only has a phone app. I want to go banging on someones door if my money goes missing!

Has anyone been using Degiro as a broker for large investments? Are there any better/larger alternatives I should be considering? (I know 'better' is a very subjective term!). Really just looking for people opinions on brokers, experience so far with.

Thanks

Use Lightyear and Trade Republic. No issue with Lightyear but have had a number of instances where I've experienced problem/ delays with transfers in/out of Trade Republic.Customer support is horrendous so will not use them anymore.

I've started on Degiro but ended up choosing IBKR when investing became serious for me. Degiro is fine but for what I've read IBKR is known for having better order execution (i.e. likely better spreads, which could easily compensate for the small fees for larger amounts), lower FX fees and a much larger range investments. It's nice to have options even if you don't plan to use them today. IBKR is just a much larger and more robust broker in all ways. Another factor for me was that ibkr operates around the world, which can make a possible future move to outside of the eu slightly less complicated.