Ex RYR, Ex EK and now working at KLM for a while now. I am Dutch and as a Dutch person this is probably the best airline when it comes to security, unions, protection etc. You basically can't be fired, no one will bother you when you're sick (only to assist in helping if you want to). Salary starts low but goes quickly. I've been here 6 years and I'm on the FO salary of EK.
Speaking Dutch has been removed but it's probably important for yourself to start learning it. We have several non-dutch speaking colleagues and they see that in the FD we all change to English but the cabin crew will not care for you...
Don't compare KLM to Transavia btw. They're completely different both with better things and worse things.
Feel free to PM me if you want. I'll help where I can.