I'm a fan of the Hefty brand latching tubs because they come in clear and opaque grey and they share 2 common dimensions between sizes, but I use them in a rack.
Really any suitable dimension, flat 28-34 quart tub should be fine for him as an adult. And either that or a 15-16 quart tub for his current size. If you go with a 28-34 so you won't need to switch him to a larger tub later, be sure to clutter it up with hides and decor to keep him at ease.
Sterilite seems to be the brand most people use, I just went with the Hefty as they're better for my rack design. But I do feel like they are slightly thicker material and therefore a little sturdier.