What is the most unique tattoo?
The most unique tattoo is one that comes from your imagination
No, "most unique" is not correct usage. "Unique" means one of a kind, so something is either unique or it is not: there cannot be different degrees of uniqueness, and something cannot be very unique or most unique. It is not uncommon to hear people say "very unique" or "most unique", but this is not correct. They should be using "unusual" if they want to use it with "very" or "most".