I show all sorts of livestock. As a matter of fact I was the 1st guy to represent horse barn in Supreme Showmanship in almost 30 years 3 years ago in 4-H. I just finished up 4-H, except my last state fair, and have been showing livestock for several years now.
The easiest to show are pigs, sheep, and goats, in that order, imo. The only trouble with pigs are getting them to work with you. Sheep are simpler since you have control over them with your hands. Goats are shown VERY similar to dogs from what I understand (I don't show dogs). Goats are a hassle with what all you have to do with them. Training their heads up, working on a collar, etc. Cattle require a LOT of attention in the sense that for their health and looks, they must be washed every single day. Cattle are also very very expensive with equipment and feed. Pigs are also expensive on feed. Goats and sheep are similar in cost, but sheep CANNOT have any other food but sheep feed and what is approved for them (copper sensitivity).
Halter breaking is difficult with cattle in the sense that they are strong (like horses) and extremely stubborn. Most people I know that show cattle use tractors and trucks to work with their cattle. Sheep and goats are easier since they are smaller.
In the end, it is all a ton of fun. I love showing livestock. It is my favorite pasttime. If you have any questions though, just shoot me one.