i like d ring snaffles, no pinching possible.
also, i like the french link snaffle type best.
no nutcruncher action inside the mouth with the 3rd link.
squeeze a regular snaffle in your hand to feel how it can be uncomfortable.
have a loose ring for my draft (only kind i could find for his size)
for that, i use those round bit guards.
cheap, can be found in rubber, or easier to use neoprene with a velcro closure that can be put on after bridle is on.

-- additional:

[updated on 2008-10-18 23:38:38 GMT]:
meant to say eggbutt not d ring.
like both, but prefer eggbutt.

Pros: snaffle bits are kind in the right hands

Cons: loose ring can pinch where bit meets ring

If you have a horse with a sensitive mouth this bit is for you. This was the first bit I ever bought and I still use it! The loose ring part helps wiggle the bit causing the horse to soften into contact. The jointed part in the middle helps directing the horse without confusion. Good also if your horse has a hard mouth they'll get used to this and gradually soften their mouth. Bit guards recommended.

Pros: Its softness

Cons: Its softness

I think a loose ring snaffle is definetly the way to go when starting horses, and even when riding the experience horse. It offers great control for a horse that has been trained to respond. Instead of using leverage to make your horse listen, you get a soft and supply response.

Pros: Easy on the horses, great for riders with tougher hands,

Cons: cannot use in western classes due to regulations.

My mare Harley has a very soft mouth and for this reason I use a loose ring frensh berdoon snaffle. I have tried other bits but Harley seems to enjoy the loose ring the best. I also ride two other horses in similar bits and find them more supple and relaxed when riding.

Pros: soft bit

Cons: pinching

I prefer the D ring snaffle for any of the horses that I ride. I havent had much time to ride lately with work and school, but this is what I have always ridden in. I think that a lot of the bits available on the market today can be harsh or not fit well in the horses mouth. I ride English and prefer this to one pieces or other types of bits.

Pros: No Pinching, No squeesing, Gentle.

Cons: NONE!