Breathless holds only 7 ppl max. All passengers face forward, like sitting in a car, and the middle and rear seats are separated by the huge engine compartment. You don't say how many on your list. Breathless is LOTS of fun, in addition to the cruise and IllumiNations, the driver will most likely treat you to a little of a thrill ride.
The pontoon boats are more like a floating living room. Nice big comfy couch/bench seats. Plenty of room for 10 ppl.
Remember, there are 5 pontoons, and only one Breathless, so if that suits you I would try to secure Breathless first, then if already booked, try to grab a pontoon.