I agree with Ellen: the gel pads by Acavallo are really high quality. For a headcollar, I'd recommend a regular leather one since they're smart and presentable. Otherwise, I'd suggest a black nylon headcollar with fleece for the comfort of the horse.
There is a range of bitless bridles out there, but personally, I use a hackamore. It's a nosepiece attachment which focuses pressure on the poll and nose and communicates to the horse incredibly well. If you're looking for a regular bitless bridle I've heard many good reviews about the Dr. Cook bitless bridle, though I have never used one myself.
For gel half pads, I recommend the brand Invictus. Even though, this half pad isn’t gel, it molds the horse’s back and makes the saddle fit better. For the head collars, do you mean halters? Therefore, I recommend Walsh halters because they are great quality and fit great on the horses.