What is a great high-protein diet for a non meat-eater?

I have removed chicken, beef, and pork from my diet for about 10 years now. I know there are those popular franchise diets out there that push “low-carb, low sodium, fat free” thing, but is there a diet system out there that would be great for someone like me that wouldn’t necessarily care to substitute meals with protein shakes? I could easily research this, but I wanted to try and get some feedback on personal experiences..