Which is the cuter animal Internet sensation - Lil Bub the kitty or Boo the doggy?
Lil Bub's owner Mike Bridavsky says: "Boo is cuter."
Referring to the two animals which have been dubbed the world's cutest dog and cat by the media and netizens, he explains: "You see Boo and it looks like a toy. Lil Bub's cute in a less traditional way. I don't think of her as an Internet celebrity. I think of her more as a hero, an inspiration and a really remarkable animal more so than just a cute animal."
Lil Bub, whose breed cannot be verified, was a rescue kitten with multiple birth defects that had a hard time finding a home. She is afflicted by severe dwarfism, giving her short stubby limbs, and suffers from a rare condition called osteopetrosis, which makes her bones grow harder and denser.
As a result, she does not seem to age and has been called a "perma-kitten".
Mr Bridavsky, who adopted her three years ago, says: "People didn't want to take Lil Bub because it was so strange- looking and so small. They were worried that it would cost a lot of money or be a potential heartbreak.
"When I saw it, I thought, well, besides being so remarkable and unique, I thought that it needed someone to take care of it because no one wanted to. And I absolutely wanted to."
He and a veterinarian did not think that Lil Bub would live very long at first, but she is now three years old and "healthier than ever".
Speaking to Life! from his Indiana home in the United States, he says he has received messages saying Lil Bub's pictures helped a student through graduate school and has been an inspiration for a chronically ill child.
Compared to the eight-year-old Pomeranian Boo, which has amassed 13 million likes on its official Facebook page since 2009 to go with plush toys made in its likeness, Lil Bub has just over 700,000 on Facebook since 2012.
But the underdog, er, undercat is now the star of an Animal Planet show, Lil Bub's Special Special.
The programme, which airs today, features American actress Amy Sedaris babysitting Lil Bub, a bunny, a guinea pig and a pony.
Mr Bridavsky says: "I've been a huge fan of Amy Sedaris. I love her show Strangers With Candy. And she was at the top of our list as people who would be perfect for the role. And when we asked her, she said yes."
Sedaris is far from being Lil Bub's first encounter with a celebrity. The toothless kitty, with its tongue perpetually hanging out, easily boasts more encounters with famous folk than the average man on the street, having met the likes of comedian Whoopi Goldberg and Hollywood legend Robert De Niro.
Mr Bridavsky recalls the surreal feeling of Lil Bub's fame kicking in for him after a meeting with De Niro at last year's Tribeca Film Festival, where they were promoting the documentary Lil Bub & Friendz.
He says: "I have to be honest. I still sometimes don't really think Lil Bub is that famous. To me, it's just my cat. Robert De Niro was more excited about meeting it than it was. I think that's when I really went like, 'Wow, this is really bizarre'."
Mr Bridavsky, the owner of a recording studio and four other rescue cats, forks out an average of US$100 (S$124) for food and supplements for Lil Bub and has devoted the past two years of his life to the cat. He spends about 80 hours a week on Lil Bub matters. These include taking, editing and uploading photos, doing interviews and producing TV shows.
He also manages the online store that sells self-designed Lil Bub merchandise. Part of the proceeds from sales is donated to animal shelters and The American Society for the Prevention of Cruelty to Animals. So far, Mr Bridavsky estimates that these efforts have raised more than US$100,000 for the beneficiaries.
"People were paying attention to Lil Bub and paying attention to everything it stands for. That made me think, you know, what does Lil Bub stand for? It's a rescue animal with special needs.
"We started selling merchandise. So, when I saw that there was a lot of money coming in, I instantly started putting part of it aside for animals in need."
Lil Bub's Special Special airs on Animal Planet (StarHub TV Channel 424) tonight at 9.30pm.