Formal:
* Hartelijk dank - This is the most formal way to express gratitude.
* Heel erg bedankt - This is also a very formal way to say thank you.
Informal:
* Bedankt - This is the most common and informal way to say thank you.
* Bedankt hé - This is a more informal way to say thank you, similar to saying "thanks" in English.
* Dank u - This is a slightly more formal way to say thank you, but still informal enough for everyday use.
For emphasis:
* You can add "veel" (very) after any of the above phrases to emphasize your gratitude, for example: "Hartelijk veel dank" or "Bedankt veel".
It's worth noting that Flemish is a dialect of Dutch, and many Dutch speakers understand and use these phrases as well.