The most popular Python would be Ball Pythons

Adult BP do not require anything larger than 30 gallons tanks 36X18X12

The bigger the enclosure, the harder to maintain and BP have VERY specific requirements that must be met. They will not be forgiven like colubrids are if their needs are not met.

Ideally you want to start with a small enclosure and upgrade as your BP grows.

You also have other pythons that have a manageable size, such as Jungle Carpet Python (good for beginners), Blood Pythons (intermediate level)…

I don’t own boas so I leave that part to someone else.