If it's just a plain snaffle, there really isn't a difference between the eggbutt and the d ring. The full cheeks, however, give you a little more control because they're harder to pull through your horse's mouth. If your horse has a really sensitive mouth, then a single jointed snaffle may not be the best choice for him. If I were you, I'd spend the money and invest in a Myler bit. I'm a huge fan of the Myler comfort snaffle with a low port barrel, it's very forgiving and popular with a lot of horses :Toklat - Horse Tack - Saddle Pads - Horse Riding Apparel - Myler Bits - Bits - Eggbutt
Oh and I forgot to add - I "technically" ride western. I team pen, trail ride, and used to barrel race, but all in an eggbutt snaffle because I prefered direct contact. It's just a matter of what's comfortable for you and your horse.