Optimal down payment amount with VA loan?

Currently looking to buy my forever home and getting a 30 year mortgage in a HCOL area.

I have enough saved for a 20% down payment in my area, however I know that as a veteran I can use a VA loan and avoid PMI no matter how much I put down.

I have a VA rating, so I also understand I do not have to pay the funding fee.

My question is this: What is the optimal amount I should put down for a down payment? I understand this will impact the interest rate? Thank you.