To be honest it depends on what you want as an adult, I agree that smaller pythons are a good starting point if you like smaller pythons or would be a great choice for kids but personally, I don't have much interest in the small pythons and I don't find the colours that interesting, so a smaller python wouldn't be my first choice.
Everyone is different and it's your own choice, maybe you will adore them and I respect that, or maybe you would prefer a bigger adult python.
Have a look at all the different types, sizes and colours to choose one you like, not everyone wants a 2.5m heavy python so if that's you, don't get a breed that grows that large, or maybe you would like a big heavy python, choose something that will suit your interest and space.
Some animals will be inherently more difficult to care for such as scrub pythons and should be avoided if you lack experience but once you choose something you like, investigate their care and learn as much as you can to see if they will suit.
Good luck ?