* Σας ευχαριστώ για όλα (Sas efharistó gia óla): This is a formal and polite way to say "Thank you for everything." Use this for someone older than you, someone in a position of authority, or someone you don't know well. "Σας" (sas) is the formal plural "you."
* Σε ευχαριστώ για όλα (Se efharistó gia óla): This is the informal version. Use this for friends, family, and people you know well. "Σε" (se) is the informal singular "you."
* Ευχαριστώ για όλα (Efharistó gia óla): This is a shorter, more concise version, suitable for both formal and informal settings, depending on your tone of voice and context. It's a bit less emphatic than the others.
All three options use "για όλα" (gia óla) which means "for everything." Choose the one that best fits your situation and relationship with the person you're thanking.