Although I can't comment on keeping ETB's, I'll give you my input on chondros. Of all the snakes I keep, chondros require the least maintanance. I now have 2.2 adults and 2.3 juveniles. Of the 9 chondros, only one gives me any trouble.
Talking to people that have kept both....most will say that etbs are a lot more trouble, especially when it comes to temper.
I think chondros would be a better choice, but be forwarned......you will want more. The color variety is greater, and in my opinion, chondros are just better looking snakes than etbs.