When I read the topic, I was like "define your ideal size... since a lot of people consider anything under 14'-16' as medium."
Logo... you might want to mention that the sizes of the snakes vary on the locality and subspecies. Also it vary based on the way they were fed and how soon they were bred.
For instance, a Central American boa (pure) rarely exceeds 5'-6', while a Colombian can certainly can exceed that.
Carpet pythons varies by subspecies as well. Jungle carpet can vary from 5'-7', Coastal can vary from 6'-9' (in captivity, in the wild it is between 8'-14'). You see a lot of 6' coastals, but that is because every bloody breeder out there is trying to get their hands in the game (for the jaguar morph), so they powerfeed them and breed them soon as they hit 6', then they slow down in growth after that. They should only be bred when they hit 8'...
Diamond pythons can vary from 6'-8', Irian Jaya vary between 3'-5', and Bredl's pythons vary between 5'-7'. (All carpet pythons)
Blood pythons are tricky as well, certain locality of blood pythons can hit 7'.
Never account for the length of the snake... but rather the weight of the snakes though... a 45 pound 6' blood python is more dangerous than say a 14' olive python, 9' carpet python or an 8' boa.