The difficulty/ease in memorizing a stack lies less, I think, in the stack you learn and more in how you go about it. Memorizing Mnemonica, which has no easily discernible pattern (part of why it is so popular), only took me about four hours over two days and a lot of people have similar stories. I used the stack memorization methods taught in Tamariz's book on the Mnemonica stack. The book is of immense value if you want to learn a stack, and if you are going to put in the work to learn one it would be worthwhile to have such a resource anyway. Aronson also has good resources and his own stack but I'm less familiar with his work.
There are objectively "easier" stacks to learn, which have built-in patterns/mathematical properties, and while I have nothing bad to say about them as a whole, I do think that learning such a stack would not necessarily be advisable for what you are trying to learn. Before I learned Mnemonica I relied on a mathematical stack, and I found that I relied on the math principles so much that I never really bothered to memorize it. Memdeck ACAANs typically require you to have a solid understanding of where cards lie in the deck, not just where they lie in relation to each other. I recommend putting in the memorization work once (which again, isn't as hard as it sounds) and having smoother performances instead of choosing a more conspicuous stack where you'll have to do extra calculation.