You could use either for now, the only problem would be down the road you would need to get a bigger tub. Also if you are using egg crate you would have to cut down all your egg crates to fit in those tubs.

Most people just use a big 18g sterilite container. I got my gray one at walmart for $4.50 and that will house tons of dubia. Plus egg crates will stand straight up and you dont have to cut anything. This size may be a little big for just 35 but it wont matter if its too big, they will grow into it in a few months if they are good breeders An if you get the solid color you wont have to paint or anything.