In general, indigos are often considered more calm and personable than cribos. However, every snake is an individual and I've noticed that any of the snakes in the Drymarchon genus can become docile. Yellow Tails seem to have the reputation as the most aggressive, but mine are both "puppy dog" when out of the cage.
By starting out with a Black Tail cribo you won't be disappointed. In fact, I would say that it is a great way to start with Drys. Once you understand the husbandry and behavior of your Black Tail then you can work your way up, and get the expensive stuff.
Good luck! Drys are great snakes.
-----
Roy Blodgett
Green Man Herpetoculture
royreptile@yahoo.com
1.1 Drymarchon corais
1.1 Masticophis taeniatus taeniatus
0.0.1 Coluber mormon
1.1 Lampropeltis getula californiae (desert phase)
1.0 Boiga dendrophila dendrophila
1.1 Corytophanes cristatus
1.2 Varanus acanthurus brachyurus (Mt.Isa)
2.2 Pogona vitticeps (snow and red/gold)
1.0 Iguana iguana
“All men lie enveloped in whale-lines. All are born with halters round their necks; but it is only when caught in the swift, sudden turn of death, that mortals realize the silent, subtle, ever-present perils of life.”- Herman Melville