By far my favorite toy for training is the human body! It’s so versatile and always up for a challenge (balance, strength, endurance, power, etc..). Paper plates also provide the basis for great upper/lower exercise drills.
For variety I do like to add other toys to the mix. However, in group fitness, we don’t always have enough toys for everybody to be doing the same thing, at the same time. So I will often sub-divide the group into two or three smaller groups and have each group use the equipment; then rotate until everyone has used it e.g., BOSU, foam roller, dumbbells.