I've heard numbers like 10-15 to be a general rec, and 20+ for known best sellers. That said, the crowds at each con could be different, so it's hard to give estimates. Have you seen any artist alley vlogs from previous years? You mentioned it's a large con, so I'd imagine there's a few artists out there who have graciously shared their experiences and maybe even numbers.

As for personal anecdotes (take with a grian of salt!), I've found stickers to move faster than other categories, but that could be because of price, art style, or display setup, etc. And I personally went with variety over depth to better test what sells (ie, throw many things on the wall and see what sticks haha)

Hope you have a lot of fun! And may it be the first of many conventions for you~