I started looking into the goats a few years ago, but got more serious about it when I ended up with a herniated disc packing a big buck out four years ago. They've been pack animals for thousands of years.
I've had horses, and will again someday, but don't have the time to care for and ride them like needed to have a good horse. They are also expensive.
Llama's and alpacas, I've never had much interest in, while they can go where horses can't, they can't go where goats can.
I used about a ton and a half of hay to feed five goats last winter. I trim the hooves with garden shears. It needs done every few months. If you some large rocks for them to climb on, it would be less often.
I didn't get mine out last summer much, so they weren't in excellent shape. I put about 50 lbs on one and 45 lbs on the other. In shape, I wouldn't worry about 60 lbs for several miles. There is debate whether you should put a max of 25% or 33% on a mature goat.
In shape, I wouldn't hesitate to put a third of their body weight on them. My two largest are about 200 lbs each. I've two two year olds, a three year old (one of my largest), a four year old and a nine year old. The three and nine year old are the largest.
They are easy going. I only use wethers (cut males). Does are fine, but smaller so more limited in weight. An uncut buck wouldn't probably be worth the trouble.
I tie them in a truck or trailer, as they will tend to get aggressive with each other in tight quarters. I like mine to be horned. There is some indication that it helps heat regulation in the summer and early fall and I want them to be able to defend themselves. Goats have been known to disembowel an aggressive dog.
I unload on the mountain and I walk. They will stay with you all day and don't have the nasty horse habit of running off to the truck and trailer if you let them get away. I've not hunted with them by my side as the panniers on the saddles are noisy. I need to make fleece or wool mantis so the brush rubbing against them won't be loud and then I'll hunt with them by me.
I'm having trouble getting the pics to link from the host, but will keep trying.