I generally do keto. High fat. Moderate protein. Low to no carbs.
I've tried the carnivore diet. Its hard to eat meat all the fucking time. I like a good steak every once in a long while but I don't cook it every day. When I cook steak it turns out like shit and I end up chewing for hours.
That said when I eat keto, I feel great and no brain fog. I feel even better on a carnivore diet.