I use fabric pots as well with FoxFarm Ocean soil and yes I agree it's hard to overwater using fabric pots. However having said that, they must be allowed to drain on the very bottom as well because if left sitting in the overflow, the container will soak all the water back up. I place mine about 1/2 cm from the ground using thick plastic coat hangers. I slide 2 underneath the 5 gallon fabric pot to allow an air gap at the bottom. I could have bought a rubber/plastic drain mat or similar, but I tend to use things that I have around the house where possible and the coat hangers do just fine.
If you can't decide on the sizre, go with the middle one...they come in 3, 5 & 7 gallon sizes so get the 5 gallon to be safe.
Now on another note, if you mean containers for storing cannabis, then glass canning jars (32oz or bigger) are the best.