Personally, I think the 7gal earthbox is the perfect container for auto flowers, makes water a breeze, and your autos can maximize their size with some lateral space to stretch the roots.
Additional the earthbox can draw unlimited fresh water while the feeder roots move about to eat. One main point of emphasis, is the plant is never forced nutrients with its water as opposed to top watering or water soluble mixes. Going wet to dry can amplify the force feeding of nutrients into your plant.
But mainly, it’s just easier and the plant is able to maintain stability and health easier thoughout the cycle with a bigger container. Just pour a gallon of water down the spout when it’s dry… that’s it with earth boxes.
The small fabric pot (in my case 5gal) is also a good option when space is more of a consideration and can be set up with an auto pot watering system as long as your soil has enough density to leach to the top.
Downsides of small pots… Not enough room for top dress, watering is more difficult and the plant will experience some extent of over/under water each day. Run the risk of root bounding them with some strains. And ultimately will require more feeding and more work.
With that said… I like to grow primarily in Earthboxes but do occasionally grow in pots. I am growing two strains (one in EB and one in 5gal for each strain) and we’ll see if there is much of a difference. How much potential am I losing in fabric pot vs earth box? I don’t think you can gain much more by going bigger than an EB with autos but it definitely makes a difference over small pots.
Beary White at 41 and 24 days from sprout.
Beary White 24 days in 5gal fabric
Beary White 41 days in Earth Box
Sweet n’ Sour 24 days in 5 gal
Sweet n’ Sour 48 days in Earth box
… See how the 5 gals go through stretch over the next couple weeks.
its the EB for me hands down: 
the EB eliminates this issue of over & under watering: only fresh water in the tank
great results just more input to get them there correct? Did you investigate the device by elon musk? 2nd bill over (4) months lowest in my history of payments: 
