The story of Fullmetal Alchemist: Brotherhood is one steeped in philosophical themes, real-world historical analogies and symbolism of alchemy and religion. The Philosopher's Stone, the nature of the truth of the world, genocide, conspiracy and more are the order of the day. But there are plenty of cool action scenes, too. It is a shonen series, after all.
The protagonist is Edward Elric, the Fullmetal Alchemist, and one of his enemies turned friends is Greed the homunculus. Greed has the Ultimate Shield, manifesting as indestructible skin, and he has claw-like fingernails and advanced martial arts skills. Not to mention his squad of battleworthy chimeras. Greed is a powerful fighter who outclasses several characters on the battlefield, but not quite all.
10 Stronger: Edward Elric
Edward Elric is not as durable as Greed, since he lacks the Ultimate Shield and lacks body armor of any kind. He can get tired in battle, and sometimes, his automail limbs weigh him down.
But he's also incredibly nimble and acrobatic, and he's a martial arts master thanks to the training of Izumi Curtis, his teacher. And of course, his elite alchemy allows him to improvise a weapon or barrier for just about any combat situation, reinforced by his expertise in science. There's little that he can't do.
9 Weaker: Captain Buccaneer
This bear-like man is a soldier stationed up north at Fort Briggs, and he embodies the concept of "survival of the fittest." He is a durable, powerful and fearless warrior, and like Ed, he has a right arm made of automail.
He gave Ed a good fight and once challenged Wrath/King Bradley, but he's not as tough as Greed, nor can he regenerate. Captain Buccaneer's attacks are rather slow, too, making it easy for Wrath to turn the tables on him and ultimately kill him when they fought on the Promised Day.
8 Stronger: Pride
The boy known as Selim Bradley is actually Pride, the oldest and most powerful homunculus. His body is a mass of shadows, mouths and eyes, and he is practically indestructible. His human container, "Selim," isn't so easily injured, either.
Greed is tough, but he's not as durable as Pride and he cannot match Pride's shapeshifting body, long piercing spikes or all-devouring mouths. When facing Pride in battle, Greed said, "Even for me, he's a monster." His assessment was correct.
7 Weaker: Maes Hughes
Colonel Maes Hughes was a popular officer in the Amestris military, since he was an impeccable professional but also warm and friendly. He's mentally tough, too, as he cares for his family while keeping up with his duties. He didn't suffer any major psychological scars from the Ishval Civil War, either.
Hughes can use pistols and throw knives with great skill, and he took Lust, the assassin homunculus, by surprise when she cornered him. But he's very human, and his offensive abilities are minimal. He can't even compare to Greed when it comes to fighting.
6 Stronger: Scar
The Ishvalan monk known as Scar is only marginally more powerful than Greed. Both of them are durable melee warriors who can outlast their enemies and deal damage over time, and they will charge right into any battle.
Scar doesn't regenerate like Greed, but he was tough enough to somehow outlast Wrath, and his destructive alchemy is formidable. He also has vast experience in fighting and killer instincts, and he can even use creative alchemy in a pinch. Greed cannot.
5 Weaker: Gluttony
This oafish homunculus serves a purpose: to be a tool. As a fighter, Gluttony is rather clumsy and slow, and he gets himself killed more than any of the others, even Lust. His arms are powerful, but rarely can he deal a serious blow.
Instead, it is Gluttony's job to contain a false Portal of Truth that Father tried to create. If circumstances allow it, Gluttony can open that portal and absorb anything in his way. Overall, though, Greed is Gluttony's superior in durability, mobility, technique and offensive power.
4 Stronger: Wrath
Wrath's case is unusual: he is a human homunculus, born a mortal man but grafted with the Philosopher's Stone when he reached adulthood. His ouroboros tattoo appears on his left eye, and he has the Ultimate Eye as a result.
Wrath can see any attack coming and dodge it, and he can even evade bullets this way, let alone sword strikes or punches. He's quick, tireless and vicious, and his sabers can slice anything apart. He has vastly more offensive power than Greed, and even if he can't regenerate much, he's difficult to hit, so it hardly matters.
3 Weaker: Prince Ling Yao
Prince Ling of the faraway land of Xing is not to be underestimated. He has survived countless assassination attempts by learning tricks and self-defense, and he can easily use a sword or his bare hands against any enemy, even homunculi like Envy the shapeshifter.
Ling is skilled, but he lacks Greed's Ultimate Shield or regeneration, and his sword doesn't do as much damage as Greed's hardened claws. Fortunately, they are on the same team, so Ling doesn't have to fear Greed's wrath.
2 Stronger: Van Hohenheim
The wandering Philosopher's Stone, Van Hohenheim, just might be the most powerful character in the series. Or at least, the most powerful good guy. He is an elite alchemist and houses the souls of 500,000-odd Xerxes citizens inside him, granting him vast power.
Hohenheim understands the true nature of just about everything, and he can perform astonishing feats of alchemy without even moving, let alone using a transmutation circle. If he can handle Father, he can handle Greed, too.
1 Weaker: Solf J. Kimblee
There is only a narrow difference between Solf J. Kimblee's combat effectiveness and that of Greed. After all, Kimblee is skilled at obtaining and using Philosopher's Stones, and he can create powerful explosions with his alchemy. He's also totally ruthless and bloodthirsty, like Wrath.
However, Greed can blitz his way through a crowd of enemies and slaughter them with his claws, and he need not fear any return fire thanks to that Ultimate Shield. He's not vulnerable to attacks from behind like Kimblee, and he's not rendered powerless by losing access to a transmutation circle. It should also be mentioned that Kimblee is a bit rusty at melee combat (which he admitted to himself).