Which animal is underrated as a pet?
Already mentioned in the answers: Rats.
It's so true. I've had many kinds of pets. Rats. Are. The. Best.
I've had three in my lifetime and when I had to euthanize my last one (she had an abscess in her throat and was unable to eat) I sobbed like I've never mourned for a human.
"People buy their kids hamsters. Hamsters are mean, they should really get them a rat." I've heard many a pet store employee express similar sentiments. Rats=disease/filth is so ingrained in us (for good reason, ie. The Bubonic Plague); that is not what you're getting when you adopt a pet rat.
Pet rats are naturally docile (I've never been bit, even when I first brought them home). They are very social and will beg for your attention by hanging from their toes until you acknowledge them and bring them out for some love. Dogs wag their tail when they're happy, cats purr, rats engage in bruxing. They grind their teeth because they are just so happy to be cuddled up next to you. Oh, and you can litter train them and they can learn to respond to their name.
If you're hesitant about their looks, get a dumbo rat-you can't resist those ears.
Also, at the time, I was unaware that pet stores are not your only option for adopting a rat. In fact, I've heard big pet stores who sell rats engage in unethical behavior. This may or may not be true, don't quote me. But, being a big rescue advocate, I would suggest you research rescue options near you first.
I was so devastated after my last pet rat died that I have not adopted another. Also, my husband shares the same hesitation about them as others with no experience. I'm working on it.