I was a bit disappointed by the Parenthood lunch bag, as it wasn't really possible to use custom ones, so I'm happy with the Picnic basket option. I like having my Sims packing food to eat outside, but has it to be a picnic basket? No!! Why not having a picnic with a McDonald's take-out bag, that you can fill wiht hamburgers? Or a bakery bag filled for sandwiches and pies? Or a dabba, with more sophisticated meals? I also turned some Sims 4 meshes into picnic baskets: the cooler, made muuuuch smaller than OR one, the cute picnic trunk but also the kids lunch box.

WARNING: You can fill these picnic baskets, you can put them in Sims' inventories, you can "set up picnic" once the basket is on table, BUT you have to place manually the basket from inventory to table, the "place picnic basket" is uneffective. I don't know why yet, I'm trying to find a fix.