I have three cats at the current moment, and have had many cats over the years, so I feel like I can answer this authoritatively. The best thing about having cats is the companionship. They are furry, friendly little creatures who want to share your life with you. Sometimes. Right now they’re making themselves scarce, only to get particularly chummy when I’m in the middle of a project.

They also provide lots of humor. Chuckie, our big orange cat, entertains with his total cluelessness. Chloe (the black cat in this picture) is just weird. For example, she goes crazy when Richard sneezes, chattering and running about as if she needs reassurance that he has not released demons into the world.
The best thing about a cat, though, is that you can’t take them for granted. They’re there when they want to be, not necessarily when you want them to be. They’re autonomous creatures with their own agendas. So, when they want to spend time with you, you know they’re there because they want to be. Or because they want food. Or because you’re busy with something else — they’re perverse little creatures.
I’d definitely recommend a cat.