What is the best online broker to use for the purchase of Berkshire Hathaway shares in euros

I am considering purchasing €50,000 in Berkshire Hathaway B shares in euros.
I am looking for recommendations for the easiest to navigate and cost effective online broker.
Any other helpful advice in relation to an online broker would be appreciated.
Is it difficult to open a Joint Account would appreciate advice on as well.
All and any advice will be appreciated.

I use lightyear and Trade Republic Dermot. Been a while some I bought anything on lightyear but think it's 1 euro/usd per trade if memory serves correctly.
Of the two I prefer Lightyear.

Not a broker, but my day to day current account is with N26, and I can invest in stocks/shares there, in fact I recently did exactly this, i.e. started investing in Berkshire Hathaway (albeit much more modest sums which I intend to repeat monthly). They recently did away with the transaction fee. You might want to consider N26 or similar alternatives (Revolut?) unless you've already discounted them and/or really want to go direct to a broker.

Be careful when opening an online broker account. Read the small print. Some default account types allow a broker to "lend" out shares you purchase to others (for a fee payable to the broker, not you). Worse still, this "lending" is used to cover short selling by others - which effectively could have a negative impact on the value of your holding.