I've had zero problems with Fidor, GLS, N26, Sparkasse in general and literally any other bank in Germany. Kraken uses Fidor for one of their bank accounts. They have a partnership with Bitcoin.de which allows buying and selling BTC instantly. Bitcoin.de even bought a another bank for their license. They're probably trying to get a bank running within the next few years. Nothing for now, but nice to know. Fidor has not the best reputation, but is totally fine. GLS is a great bank overall. N26 is okay, nothing you should totally go for. Sparkasse are normally all great, but this can depend on the location. I guess you're trying to get a personal account. This should be possible with all of them. Opening a business account for crypto is probably not easy with all of them. At least Fidor does it and Kraken uses them. That's a good sign I guess.