Mine is “What is your current favorite quote and why?”
What am I intentionally ignoring?
What can I do in one hour or less to make my life better?
Mine is: what are you grateful for?
Write a letter to your past self (10 years younger than you are today). Then write another one to your future self (10 years from now).
If I’m particularly stuck, but know that I have something that I need to process/consider/write about in order to understand it, I’ll sometimes start with a particularly poignant line of a song, poem, etc., that somehow has relevance to the thing I am trying to process into writing.
There are a number of artists and phrases that trigger deeper thought within me where just asking myself a question to get the tap flowing would be less effective.