When you first get your Anova, just use a few different inexpensive containers to see what works best for how and what you cook. My cooking needs will most likely vary from yours. There are times that I can use a stock pot, a square container, or a rectangle container. I might need a cooler. I have ordered one of the Coleman Stackers and will do a review on how it works as a sous vide cooking vessel when it finally arrives.
I was heavily leaning toward the Rubbermaid square containers because the sous vide lid fits multiple sizes. Then I found that when I cook for five or six, I want to stand the steaks or chops up using a rack and that doesn’t work well in a square container but does in a rectangle. Now, I’m looking to LIPAVI containers but the downside is that I would need multiple lids.
Therefore, I have remained undecided and am still using my stock pot or $5 containers from Walmart. There is an advantage to inexpensive containers from Walmart, I can freeze water at the bottom of them for using the ice bath feature and not worry about the container breaking from the expansion.
Note None of those links are affiliate links and I don’t sell any of those linked products. Just giving you some ideas.