Armour: Fighter gets scale, Paladin gets Plate - Advantage Paladin
The Paladin has the advantage in straight AC bonus. However, Scale has no check penalty, while Plate has a -2. With the Armor Specialization feats, Scale gains 1 AC and removes its movement penalty. Plate simply gains 1 AC. I'd say they're even, if anything, and perhaps with Scale even beating out Plate. But Paladins can still use Scale, so they're even.
Defences: Fighter get +2, Paladin gets +3 - Advantage Paladin
The Fighter is really good at one defense, the Paladin is kinda good at all three. I almost wanna call this one a wash, but I suppose we can give it to the Paladin.
HP: Same
Healing Surges: Paladin gets 1 more
Same HP, Paladin has one extra healing surge, to play into his role as a Defender/Leader. That extra healing surge is meant to be used in a Lay on Hands.
Skills: Fighter gets 3, Paladin gets 4 - Advantage Paladin
Yeah, this one goes to the Paladin, even though it's basically 3.5 skills, since one is forced.
Weapon Proficiencies: Fighter gets Military Ranged over Paladin. Which nets out to be a +2 to hit with bows, unless the Paladin is an Elf and gets them for free anyway. - Advantage Fighter, maybe.
Fighter definitely wins in the weapon department. On top of having more proficiencies, he's better at wielding his weapons than the Paladin is.
Marking - Fighter has better means of marking, the Paladin mark is vastly stronger. - I call it a wash.
I wouldn't call the Paladin's mark stronger. He can have one foe marked, and deal damage to it if the enemy doesn't attack him. With a few Close Blast (say, Dragon Breath for a Dragonborn) or Close Burst 1 powers, the Fighter can mark multiple enemies. The Fighter can also easily increase his damage done by marking, with better weapons, feats, stats, and magic items. The Paladin can only increase his mark damage via stat increases. Advantage: Fighter.
Role - Fighter has better control over NPCs (I.E. Leans towards controller.) Paladin has healing and ally boosts (I.E. Leans towards leader.)
Actually, you've got their roles a bit mixed up. The Paladin is, indeed, a Defender/Leader. However, the Fighter is a Defender/Striker. And well, there's just no winning this one. They serve two different purposes. ^_^ The Paladin is better at aiding his allies, the Fighter is better at kicking enemy butt.
Powers: Damage is a wash as far as I can see. The fighter has more powers that make him seem tougher, which are pretty much negated by the Paladins ability to heal himself at will. ... Looking more closely the Paladin can do more damage and gets ranged attacks as well. - Coolness probably goes to the fighter but for usefullness I say advantage Paladin.
I have to say the Fighter wins this one hands down. The damage may seem roughly equal, but keep in mind that the Fighter is making FAR more attacks. He gets OAs when everyone else simply doesn't. He also hits more often than the Paladin thanks to his +1 attack for One/Two Handed weapons.
Why exactly should someone pick a Fighter over a Paladin? And don't say "Roleplaying", everytime someone complains they want an archer fighter or swashbuckly fighter they get pointed at the Ranger and told to imagine it has a different name, so obviously the same can be done here. So stuff it. Mechanically what does the fighter player have that the Paladin player envies?
What does the Fighter have that the Paladin envies?
A better Marking mechanic.
Better chance to hit.
Higher damage output.
They also simply play entirely differently. A Defender/Leader and Defender/Striker are two very different beasts. Some people would be attracted more to one than the other.