Horse and mules can carry MUCH more than llamas (not alpacas). BUT, they and their equipment (tack to trailers) are MUCH more expensive and it is necessary to work with them much more.
In a situation where you can use them regularly, no llamas in the world can even be mentioned in the same breath with experienced mountain horses or mules.
HOWEVER, for most people, llamas are infinitely easier to "get along with", don't spook, eat less, cost less and DO NOT require a drink on a daily (or even every other day if it's cool or moist weather, as it is during hunting season).
It really does depend on what you're doing and your circumstances but if you are really asking, think hard about the llamas, because they are SO much easier. (Yes, I've done both.)
Within the shadows, go quietly.