Um, dogs (not sure if you just meant yappy little dogs or all dogs) are extreeeeeeeeeemly useful and are one of the animals that have aided humans the most throughout our journey through civilization. In fact most breeds of dogs simply want to serve you and nothing else, and they were created to serve a purpose and each breed is fine tuned for something. And you can teach them to do practically anything you need them to do. You may not know what their purpose is when you first meet them but they can surprise you. My aunt has a Viszla which are not mousers, but he caught 27 mice in her apartment (yes she moved) and deterred some crazy people from trying to get all the way in her window. Then of course there are the guide dogs, bomb sniffing dogs, companion dogs, cancer detecting dogs, police dogs, search and rescue dogs, fishing dogs, attack dogs, guard dogs, epilepsy dogs, therapy dogs, big game hunting dogs, rat catching dogs, flushing dogs, war dogs, herding dogs, sled pulling dogs, bird dogs, watch dogs and just all around amazing dogs that come to their owner's aid when most needed.
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Anywho... my list is
1. Dogs. I've had one ever since I was 3. I come from a hardcore big dog farming family and even though none of farm now there's always a dog. Dogs are amazing creatures and after I did a paper in high school about how they influenced how humans evolved and it was really cool. They're the only animal that inherently knows what a human pointing a finger in a direction means and are very good at reading our facial expressions. They also make me very happy.
2. Cats :3 I've never had a kitty but I wuv them. No one in my family is overly fond of cats mostly because of allergies and the older folks kind of view them as pointless, except my aunt who had a himalayan (only cat I've never been allergic to). So, to compensate, I cat sit for other people and play with the neighborhood cats. One thing I really like about cats is that they always seem to know something that you don't, and they know this. I plan on getting one one day and getting allergy shots
3. Horses/ ponies. I horseback ride and have loved them since I first saw MLP a loooong time ago. They all have really diverse personalities, can be very playful (one I knew like playing "throw my dish out of my stall and watch the humans run to get it" "grab the construction cone and gallop away from the humans" "fetch the jollyball, pretend to give it to the humans and then hold it above their heads"), are very in tune to what you are feeling, and the partnership between you and the horse is amazing. I like drafts best.