Sumatrans come from (you guessed it) Sumatra, and are the most frequently imported of the blood pythons. Malaysians haven't been imported with any frequency over the past 20 years, and are reported to have more hostile temperaments than many. I have a pair of CBB yellow Malaysians that are just dream snakes - docile & nice to work with, but they're also extremely alert & fairly hissy.
Bangka Island bloods are a bright red insular form, and WC animals can be holy terrors to work with. It takes a lot of work to acclimate them - some of the Bangkas I've had in captivity for over a year will go out of their way to bite me when working with them. They're extremely defensive animals in my experience.