Welcome to BYC. Glad you decided to join our flock. I would suggest either Silver or Golden Sebrights for showing. They are cheerful, colorful little bantams that all catch the eye. Please feel free to ask any questions you may have. We are here to help in any way we can. Good luck in showing your bantams.
It can be hard to decide what bantam breed to show. However, here are some pointers to decide which breed is best for you:
What is your climate? Don't pick a single comb bantam breed if you get cold winters, as their combs can get frostbitten without supplemental heat, diminishing their show potential. Rose combed breeds (such as Wyandottes) or pea combed breeds (such as Cornish) are better.
What type of bird do you like? Some people like fluffy breeds with unique feathers, while others enjoy the ordinary colors and breeds.
Do you want to win? True, any breed can win. But, some breeds have already been perfected a lot and will have a greater chance. These breeds include White Rock and White Wyandotte bantams. Black colored bantams are also usually competitive.
Do you want to spend lots of time preparing for show, or not much time? Breeds such as Silkies and Cochins require more maintenance than for example, Chanteclers. With feather footed breeds and birds with crest, like Polish, you have to worry about mites and lice more.
What is common in your area? If breeds are relatively common, it will make it easier to find showing stock. It's best if you don't have to ship birds in, as it is expensive and can stress them out. It's also good to have a breeder nearby to help you out in breeding and exhibiting.
Do you want to spend a lot of time cleaning a chicken? Don't pick a white breed/variety if you don't want to spend at least 20 minutes per bird washing.
Are you going to consider breeding your show birds as well? Some breeds are hard to breed. For example, most Cochins need to be artificialy inseminated to insure fertile eggs. Wyandotte males may have trouble with fertility as well. Some breeds, like Sebrights and Rosecombs, have low vigor and you may lose chicks and have poorer hatches. Japanese bantams have a lethal gene that will kill 25% of the chicks before they hatch.
Do you want a sweet bird, or do you not mind a flighty one? Some breeds are flightier than others. Leghorns, for example, are often flighty. Wyandottes, Cochins, and Silkies tend to be sedate and gentle.
Do you want to save a rare breed? If so, pick a not-so-populuar bantam breed. There are lots out there that you don't see often in showrooms, but are still great birds. This includes Dutch, Faverolles, Andalusians, Delawares, Minorcas, and more.
Are you prepared to "dub" birds? This means that your cut off the comb, wattles, and earlobes when they are young. This has to be done to game type breeds (Old English Game, American Game, Modern Game) in order to show. You can get around this by only showing young birds (only cocks have to be dubbed), but a smoothly dubbed cockerel will usually still beat an undubbed cockerels.
And, another thing to remember: If you're going to show, DON'T by birds from a hatchery. Hatchery birds aren't bred to the American Poultry Association Standard of Perfection. They often are smaller in size or have the wrong color or characteristics. You'll be dissapointed in hatchery birds if you want to show, even at local 4-H shows. Go to a reputable breeder.
Hopefully, this helps you out! I would personally recommend the Wyandotte Bantam. They are bred to a high state of perfection and are usually docile. Rocks and Leghorns tend to be nice birds as well, though I don't have any personal experience with them.
I'd stay away from these breeds, for various reasons:
Cochins, Silkies, D'Uccles, Faverolles (because they have feathered legs, and you don't want that)
Polish (because of the crest- you'll have a problem with mites, which you don't want if you're a beginner)
Old English, American, and Modern Game (often sweet, gentle birds, but the mature cocks have to be dubbed)
Rhode Island Red (these aren't so bad, but there are many poor quality birds out there. It is hard to get the correct color- if you want a challenge, go for it!)
Rosecombs and Sebrights (often have low vigor and hatching problems)
Japanese Bantam (could be a good choice, but be aware that 25% of chicks will die in the egg. Another percentage can't be shown because they'll have too long of legs)
Seramas (yes, these are cute little birds that are showy. But it is really hard to find good quality birds. Most of the Seramas I see are too large and don't show correct type)
Wyandottes7 gave you some great advice. There are many bantam breeds to choose from; what you eventually pick will depend on your preferences. My favorite bantam for showing, though, is the Wyandotte bantam. They are gentle, beautiful little birds that are usually quite perfected in type. That means they do well, at both 4-H shows and higher levels.
I also really enjoy my Dutch Bantams. However, that breed is rather rare, and it is hard to find good ones.
Whatever you decide on, have fun with it! I've been showing chickens for four years, and have a great time doing so.