(Misunderstood Gamma-Irradiated monster)
You know the story, right? Emotionally repressed scientific genius Bruce Banner is caught in the blast of an experimental gamma bomb and transformed into a raging green force of violent emotion. Hey, it's a good origin story: there's action, there's Freudian subtext, and a whole bunch of tanks get smashed up.
(Fun Hulk fact #1: the reason our Bruce was in the way of the bomb in the first place was because he was trying to save this dumb punk teenage boy named Rick Jones. This Jones kid's a story in himself - the sorry bastard spent the best part of the 1960s being passed around between the alpha males of the Marvel superhero community in the role of 'sidekick' or 'partner'. Feel free to snigger in a knowing Werthamesque fashion.)
(Fun Hulk fact #2: Banner's forename was changed to David for the 1970s TV series because it was felt that the name Bruce was 'too gay'. Ahem. See Fun Hulk Fact #1.)
Anyway, the thing you have to understand about the Hulk is that he's just kind of dull. Yeah, the guy gets mad, he smashes stuff up, but then what? All this wandering around in a haunted paranoid daze through small-town middle-america… it's depressing, is what it is. The Hulk would be a lot cooler if he had a secret hideout, some sexy sidekicks and a bunch of cool gadgets, frankly.
(Fun Hulk fact #3: there was a period in the 90's when they tried giving the Hulk a secret hideout, some sexy sidekicks and a bunch of cool gadgets. Not to mention a genius-level IQ, a nice line in sarcastic wit and a fairly radical political consciousness - the tale where the Hulk travels to Israel to confront far-right zionist extremism being a personal favourite. I'm not making this up! It was ace! Didn't last, needless to say.)
He's big, he's dumb, he's basically quite boring. But he does have funky purple pants.
(Tragic Cosmic Ray-irradiated monster)
Okay, so the Thing is basically the Hulk. Big dumb monster given to knocking down buildings and fighting supervillains. There are, however, several crucial differences, and in every one of these the Thing comes out on top. Firstly, there is the fact that whilst the Hulk is a mangy directionless homeless bum, the Thing lives in a big sci-fi skyscraper. Thing Bling, baby! What's more, he is regularly to be found hanging out in such ultra-exclusive joints as the Blue Area of the Moon, the lost city of Atlantis, and the Negative Zone. The Hulk just kinda mooches around the desert. He probably eats out of garbage cans, for gods sake.
Second is the related point that while the Hulk is basically a johnny no-mates, feared and hated by a society that blah blah fucking blah, the Thing gets to hang out with the Fantastic Four. Come on, living with your best friends, having adventures - it's like a neverending student flatshare paradise. With robots!
Thirdly, we may consider personality. As we all know, personality goes a long way. And whilst the Hulk can barely string a sentence together besides the (admittedly entertaining) "Hulk Smash!", the Thing a.k.a. Ben Grimm is a complex, nuanced and genuinely charming character. He embodies the mythological toughness of New York in the first half of the 20th century - the street-smart wiseguy ideal. With his long-running feud with the 'punk kids' on Yancey Street and his artful deployment of such colourful phrases as 'My Sweet Aunt Petunia' and 'Wotta revoltin' development', it's like he walked straight out of a Damon Runyon story. You have to love this guy.
And what's more, he says "It's Clobberin' Time!". Come on!
Finally, there is the area of aesthetics. The Hulk is green, which no-one's going to try and say isn't cool. But the Thing is a GUY MADE OF ORANGE ROCK! Good work, Jack Kirby!