I wouldn't say humidity is the only difference by a long shot. The temperatures that need to be provided, viv size, substrate, whether arboreal or ground dwelling, how big they grow etc etc. There are also species-specific things that need to be considered, i.e hognoses being rear-fanged. The needs of each species you consider should be researched and provided for. The point I was trying to make was that with a bit of effort, you shouldn't be limited to just corns.