I like the Rinehart 3D targets, because they are durable and easy to remove arrows from.
This is an example of one from 3 Rivers. If you want to save money, look around for a blem, because after you have shot it and it is out in the weather for a while you couldn't the difference from a new one after the same amount of time.
I think a 3D animal helps, because it helps you learn to aim for the kill zone rather than a bullseye. You can learn to be just as good a shot shooting at a bullseye, but when we change the target we introduce a little confusion into the mind that could cause you to forget some of your good form.