It depends on how you trade. Fiat or not? Leveraged? Futures? Frequently? Algorithmically?
Binance global has a wide choice of crypto and tight spreads for crypto-crypto trading, but not fiat. Binance US has fiat trading. Bittrex has a good choice of both crypto-crypto and fiat-crypto markets. BitMex is popular for leveraged futures trading.
Insert 10K euro in your kraken account, trade it to bitcoin or other crypto, wait a few hours or days, get it back to fiat and start trading again once you think it is the lowest price!