Using just the core rulebook and the advanced player's guide, what would be an optimal build for a fighter using 25 points for point-buy character generation? Assume it's a level 10 fighter intended to focus on dealing high damage to single targets consistently each round.
In general, two-handing with Power Attack is the best start to DPS. Now with the APG there's the "Two-Handed Fighter" fighter variant that helps it even more.
At level 10, you should be able to easily have a 22 STR (start with 18 +2 racial +2 levels) plus magical strength enhancement of +4. Of course you have to dump a bunch of other stuff but you want DPS so here's the DPS. 26 STR (+8).
If you're human, you have 6 normal feats and 6 fighter bonus feats.
Your BAB is +10/+5. Power attack gives you a -3/+9 to hit/damage. Weapon training gets you +2/+2. Weapon focus and weapon specialization get you +1/+2. So when power attacking, which generally you should, you're at +18/+13 to hit and +21 damage.
Now you have two scenarios - standard action and full attack.
Standard action - with overhand chop (2wf variant) you get double STR bonus to damage on the attack. Vital strike gets you double base damage. Assuming you're using a greatsword, that's 4d6+29 damage.
Full attack - backswing (2wf variant) gets you double STR bonus to damage on the second attack. Then you take Furious Focus (APG feat) so the PA penalty doesn't apply to your first attack. Now you're at +21(2d6+21)/+13(2d6+29).
Toss in Improved Critical, Critical Focus, Cleave, and Great Cleave. And then, you know, 6 other feats you want. That's without getting fancy with tricks, I don't like it to be too cheesy, but there with some solid basics you're tossing in a good average damage. Of course any rounds that you benefit from buffs, Enlarge, etc. is a good addition.
Here, I Hero Labbed up a level 10 two weapon guy and spent his money on an optimal damage (not really AC or anything else) loadout. I did give him step up, disruptive, and spellbreaker because if you are focusing on single opponent combat the BBEG is likely to be a caster a lot of the time.
TWO HANDER GUY CR 9
Male Human Fighter (Two-Handed Fighter) 10
NN Medium Humanoid (Human)
Init +2; Senses Perception +0
AC 23, touch 11, flat-footed 22 (+12 armor, +1 Dex)
hp 75 (10d10+10)
Fort +8, Ref +5, Will +3
Spd 20 ft.
Melee +3 Adamantine Greatsword +25/+20 (2d6+19/17-20/x2) [ +25/+17 (2d6+28/17-20/x2) when power attacking] and
Gauntlet (from Armor) +18/+13 (1d3+8/20/x2) and
Unarmed Strike +18/+13 (1d3+8/20/x2)
Special Attacks Backswing, Overhand Chop, Shattering Strike +3, Weapon Training: Blades, Heavy, Weapon Training: Pole Arms
Str 22/26, Dex 14, Con 12, Int 10, Wis 11, Cha 10
Base Atk +10; CMB +18 (+21 Sundering); CMD 29 (34 vs. Disarm37 vs. Sunder)
Feats Cleave, Critical Focus, Disruptive, Great Cleave, Greater Weapon Focus: Greatsword, Improved Critical: Greatsword, Power Attack -3/+6, Furious Focus, Step Up, Vital Strike, Weapon Focus: Greatsword, Weapon Specialization: Greatsword
Skills Acrobatics -3, Climb +7, Escape Artist -3, Fly -3, Intimidate +10, Knowledge (Dungeoneering) +10, Knowledge (Engineering) +5, Ride +5, Stealth -3, Survival +10, Swim +7
Combat Gear +3 Adamantine Full Plate, +3 Adamantine Greatsword; Other Gear Belt of Giant Strength, +4
Backswing (Ex) Attacks after the first in a full attack receive 2x STR bonus.
Cleave If you hit your first target, attack an adjacent target at the same attack bonus in exchange for -2 AC.
Critical Focus +4 to confirm critical hits.
Disruptive +4 DC to cast defensively for those you threaten.
Overhand Chop (Ex) Single attacks with two-handed weapons receive double STR bonus.
Power Attack -3/+6 You can subtract from your attack roll to add to your damage.
Shattering Strike +3 (Ex) +3 Sunder and damage vs. objects.
Furious Focus If you are wielding a weapon in two hands, ignore the penalty for your first attack of each turn.
Step Up You may make a 5' step closer when your opponent makes a 5' step away from you.
Vital Strike Standard action: x2 weapon damage dice.
Weapon Training: Blades, Heavy +2 (Ex) +2 Attack, Damage, CMB, CMD with Heavy Blades
Weapon Training: Pole Arms +1 (Ex) +1 Attack, Damage, CMB, CMD with Pole Arms
You could also consider adding a 2H with Reach (polearms) to give yourself a little versatility and the ability to Attack of Opportunity anything that approaches you. You could take Quick Draw and switch to your 5ft range, or you could 5 ft step back and attack each round. The combination of weapon options is one strength of Fighters. If you choose not to take up Weapon Training Polearms, consider changing your second Weapon Training to an Advanced Weapon Training (from the Weapon Master's Handbook). None of them are offensively geared, but there are some that help keep you in the fight.
Also, having a weapon with reach (like a Lucerne Hammer, which does D12 base damage) gives you the ability to hit enemies 10 feet away, and an attack of opportunity on anyone who moves up to be able to attack you (unless they just move 5').
So having a reach weapon gives you many more opportunities for attacks of opportunity and also for cleaves/great cleaves etc...
This, combined with the fact that its a two handed weapon, means you could take all of the feats described by the person above, and also invest in some Dexterity and combat reflexes, and maybe the cleaving finish feat, or Lunging (which can give you a +5ft reach, so a 15 foot reach in total - thanks to the poster below for correcting me on this).
The one problem with 2 handed weapons and power attacks and lunging is that these can lower your AC (no shield and -2AC penalty for lunging). So you need plenty good armour and HP to make up for this.