Either one is appropriate. I see by your avitar that you ride in a D ring snaffle I would start with that, then possibly as your equine is progressing you can switch to a more traditional driving bit. But this is not necessary, or even required.
My motto, Do what works, or, If it ain't broke , don't fix it.
She's already broke to drive, she's off the track, so I'm just doing ground driving right now since I don't have a full harness. I would really like to get a harness and buggy for her after I get another job and finish our show season :)