You absolutely need Power Attack.
Frankly, I think every fighter needs Power Attack, Expertise, Improved Initiative, and Combat Reflexes. Or, at least as many of those as his stats allow.
You just can't compare these with other Feats. It's really insane.
Power Attack: you'll have plenty of extra attack bonus once you get to high levels. ACs just don't scale up as fast as attack bonuses, in my experience, even when your target is another tank. On the other hand, you'll NEED the extra damage to counteract the ever-increasing HP totals.
This also leads to the ever-popular Cleave.
Expertise: you'll have plenty of extra attack bonus, and if you're the tank of the group you NEED your AC to scale up as fast as your attack bonus. See the trend? I'd get Power Attack first, though.
Combat Reflexes: For some fighters this isn't as important, but I've found this Feat pays for itself even if you only get ONE extra AoO out of it. There are too many times when I've run up against a caster who thinks "ha ha, he used his AoO on that other guy, I'll be safe casting now!"...WHAP...fizzle
Of course, my main fighter-type person uses a reach weapon, so I get a lot of movement AoOs. But the principle holds.
Improved Initiative: You just can't realize how good this is until you see it in action. If you're in a group and you always wait for the Mass Haste then sure, it's not quite as strong, unless you're the one casting the Mass Haste. But solo?
If I'm fighting Bob, and we have equal Initiative modifiers, I have a 47.5% chance of winning the roll, he has a 47.5% chance of winning the roll, and there's a 5% chance of tie.
If I take Improved Initiative, I now have a 66% chance of winning, he has a 30% chance of winning, and there's a 4% chance of tie.
Those aren't the sort of odds you want to be on the short side of.