I've made this recipe so many times, and what I love about it is that it's so customizable!
I've used krab, sashimi-grade raw tuna, sashimi-grade raw salmon, and unagi (eel). I usually substitute daikon radish, as it has more of a crunch than cucumber and I enjoy the flavor more. I've also used raw zucchini for someone who didn't like cucumber and was unsure about the daikon. In the photo, I also added furikake and garlic chili crisp. I always add avocado. Sometimes I do the seaweed, but it gets soft really fast so lately I've been skipping it.
I eyeball the spicy mayo when I make it, but generally use prolly 1/2 mayo and 1/2 sriracha bc I like it spicy. :) I also add a dash of soy sauce, as well as a bit of wasabi for even more spice (it's also easier to combine all the sauces together imo).
I've found that 1/2 cup (uncooked) rice is good for a single serving.
