This question is about thank you for your time.
Say, "Thank you for your time," with a written note. This can be a handwritten card or a typed email, but making an effort to send something tangible to say thank you goes a long way.
Thanking someone for their time in person is also appropriate, though. You should always do this at the end of an interview or other meeting. A written thank you note should be an add-on to this in-person thank you, not a replacement.
When you do write a note to thank someone for their time, be specific about what you appreciate about them giving up that time for you.
Are you grateful for their help with a project? For the opportunity to interview? For their feedback on a presentation? Whatever it is, let them know. This makes your note more personal and genuine because it doesn't sound like it's from a template. (Which you should never use, by the way.)
When you're writing a thank-you note after a job interview, open with what you're thanking them for and then incorporate a brief note reaffirming your interest in the role (or letting them know if you've chosen to move in a different direction and are no longer interested).
After that, include an invitation to reach out to you with any additional questions and your contact information. This will further demonstrate your interest in the role. Close with another note of thanks and your signature.