Back heat or belly heat?

I'm building a rack for my soon to come new bp's and just wanted some prefrences as to back heat or belly heat. Which is easiest to maintain steady temp/ keep maintained during lower temp season and what not? Thanks for the advice!

http://ball-pythons.net/forums/showt...elly+heat+back

This may be useful

very useful thx, guess thats where the search tool comes in handy eh? =P