I used 1" x 2" 14 gauge welded wire. That was after a running battle with a skunk that kept digging it's way into my horse barn to steal cat food. It managed to slip through a 2" crack.......so I decided 2" x 4" wire was too large.
If you have weasels, even 1" x 2" may be too large. Especially so for that skinny little least weasel if you have to deal with one of those.
I'm leaning towards using the rabbit guard. It seems stronger to me for some reason. This will only be about 18-24 inches around the bottom of enclosure. Hardware cloth with go around the actual enclosure.
Neither of the above....tho those screen shots are not as informative as links would be. 3x4 is too big a mesh...and 1/2" will rot away too fast and harder to lay flat, IMO.