100% recommend the Vietnamese. They are easy to keep and reproduce much faster and more volume than others. They will eat a lot of different leaves - oak, blackberry, raspberry, rose, etc. and romaine lettuce during winter. You could feed romaine all the time, but that's a boring diet that prob doesn't offer much in terms of gutload. Throw them in a screen cage (the chameleon kit 16x16x30 is perfect), add a mason jar or bottle of water to hold the cuttings.... or you can make a tube out of thin PVC to attach to the sides (so leaves/branches are higher up like tree branches). Lightly mist 1-2x a day.
They are an absolute favorite feeder for chams of all sizes. Nymphs are great for little ones and smaller species. An adult cham will enjoy them, even at full size. They are very soft bodied - if you picked one up with tongs it would fold over like a wet noodle.
I would not recommend Aussies, or any other very thick bodied stick. They not only have a lot of girth, but they have a very strong grip, and put up quite a fight. They don't bite or scratch the chameleon, but they (Aussies) get a super-glue grip on screens and sticks - way worse than hornworms - and they wiggle like a rattle when being eaten. They just put up too much of a fight. Vietnamese, Pink Wings, Indians, etc are the opposite and an awesome feeder.
They are regulated and potentially envasive/destructive... so they should be kept in a way to ensure there are no escapes, and no accidentally discarded eggs.