square, round, I use them both, especially the smaller sizes. I think putting square pots edge to edge to conserve space wouldn't work for me as I like to turn the plants in relation to the lights quite often. Square pots wouldn't make this too easy. I've used the 3 gallon bags for two grows now and I like them. I don't think I'd go any bigger. I transplant into 5 gallon pails if I need to.

Thank you for the kind words too. Good luck with your grow.

Shov