Ball pythons don't really "bask"... But if you need to keep the ambient temps up then I would definitely recommend a red, blue, or black, bulb because it doesn't bother them at night. You could always go with a ceramic heat emitter too.
ceramic heat emitters are amaziong they last like 5 years but are warented by zoo med for 2 year!! it breaks or blows out they send u a replacment!