What succession of sizes of plug trays, flats and pots do you use?

Bh, I was looking at the teku black square pts on ebay and he 7x7 going by the reviews aren't the same relative strength as the 11s or 13s. Back to te drawing board. I like that neat stack of pots scrungee Saves so much time and effort by standardising, organizing and having everything mise-en-pace rather than rummaging in a jumble at the last minute , don't you think.