I ride Dallas in the Herm Sprenger Dynamic RS D-Ring Snaffle, and he absolutely loves it. I owned him for 7 years before I got this bit and out of all the bits I've used on him it is by far my favorite. I really like the way it sits in his mouth, and he's very comfortable in it.
On Shaymus I use a D-ring snaffle with a copper mouthpiece. He's not as picky with his bits as Dallas is, but I've found the one he seems most comfortable in.
Every horse is different and I have a large collection of bits encase I need to change it up or something.