Is there a reason you need to keep small chameleons? Is it a space issue?
Because if you do have a bit more space, there is no doubt that a Veiled chameleon would be the best starter chameleon. They tolerate a greater range of temperatures and humidity than most other species, and are generally hardier than a lot of species. Also, because of their proliferation as 'pet' chameleons, they are generally a lot less expensive than other species.
That all adds up to make them a great chameleon to learn with. They tolerate quite a few beginner mistakes.
Panthers are usually ranked second for beginner chams, since they are almost as tolerant as Veileds.
Rudi's chams require more specific conditions to be kept in, and I wouldn't recommend them to a beginner. Also, a lot of the stock sold in your country is WC, and those animals are even more tricky to deal with.
Pygmy chams are also a little more difficult for the beginner since due to their size and behaviour, it is harder to diagnose problems as they arise.
It must be remembered that chameleons are some of the most difficult reptiles to keep, so if you are just starting out with them, it makes sense to choose a chameleon species that is relatively easier than others (even Veileds are not 'easy' to keep - they're just not as difficult as some)