Cat Fight: Heathcliff vs. Garfield vs. Tom.

Tom, he's battle tested.
Heathcliff would get distracted by an attractive lady cat.
Garfield, in similar fashion, would stop in his tracks at the sight of lasagna. Or a nap.

Tom would win.

Well, Tom is persistent as others have said and he can withstand a lot of punishment. Garfield can outwit the likes of Jon and Odie in any circumstance but these cats are a much tougher proposition. Heathcliff's a lover not a fighter. I think Garfield can take this.

Eek the cat is the superior cat

Tom, because he has durability

When Cringer becomes Battle Cat, he is formidable.

Tom always loses. Garfield is too lazy to fight. I barely remember Heathcliff. Jerry makes an appearance halfway through and foils all the cats, winning the fight.

My thoughts exactly. Toms a wily veteran continually up against stiffer competition in Jerry. He’s a league above the other two in a fight.

I know this is old, but I encountered it, and I was inspired to register to reply because from reading through, I can tell most of the people commenting are not familiar with all three properties. I am.

Most people are getting this very wrong. Here's how it would really go, in the order that they'd go out:

Garfield

This is not a dig against the character. I was a bigger Garfield fan than either of the other two. It's just that the reality is, Garfield's a fat, lazy cat who hates Mondays, loves lasagna, and thinks sarcastic things. He's not a fighter in any sense of the word. He either sits back and watches (while making sarcastic commentary) if they'll let him, runs away if he's attacked and can manage to escape, or summarily gets his orange behind handed to him. Regardless, he's the first to go.

Tom

On the one hand, Tom is battle-tested, yes. He fights constantly, and he's somewhat capable of it. He's even had occasion to prevail over Jerry. On the other hand, the fact is, his chief rival is much smaller and physically weaker than he is, and he still usually loses. He especially loses to Spike (the bulldog), who he doesn't really even try to fight. Tom is slightly more successful than, say, Sylvester, and he's certainly more of a fighter than Garfield, but he's still fundamentally a born loser. He's the next to go.

Heathcliff

Oh boy. This is where it gets crazy. Garfield is much, much closer to Tom's battle prowess than Tom is to Heathcliff's. Tom fights a mouse in a house, and he usually loses. Heathcliff has a whole neighborhood on lock, and he never loses, not even against the local bulldog—who, incidentally, is also named Spike. In fact, Spike is generally terrified of him. Heathcliff regularly wins out over other cats (even taking on three at once and beating them all up easily), dogs and even humans who manage to somehow attract his ire. In one episode, he briefly became a circus performer, and he started screwing with, among other things, one of the lions there.

Heathcliff doesn't just beat Garfield and Tom, he also beats Odie (which admittedly isn't that impressive), Tom's Spike (which is), and anyone else you care to throw at him. There's no contest. He's canonically that ridiculous. Tom and Garfield could gang up on him, and he'd still win without even breaking a sweat.