Canvas is compared on ounces because that is the only number anybody publishes. None of the four questions below is about ounces.

Duck or plain weave?

Duck is double-filled and packs far tighter at the same weight.

A 10 oz duck beats a 12 oz plain weave, and costs less.

Combed or carded yarn?

Combed is smoother and stronger for its weight; it prints fine detail better.

Carded is cheaper and right for heavy utility work.

Pre-shrunk or not?

Untreated cotton moves three to five percent on the first wash.

On anything printed, that decision belongs before the screens are made.

Is there a base?

A boxed gusset gives the bag a footprint so it stands up loaded.

Ask whether the base seam is bound, too. That is where bags wear through.

Then choose the colour

Enjoyable, and safely secondary to the four above.