False sentiment there. The majority of combat maneuvers compare unfavorably to using the same action to do nothing but straight out attack.
It doesn't have to be 'great', just compare the opportunity costs:
Bull Rush - Standard action or Charge. So at a minimum it needs to compare with a full attack or a move + attack. The furthest you're going to get this without hyperspecializing is 10ft. A free action counters the effect. A full attack, or a charge easily deals more than 10d6(a 100ft cliff) or even 20d6(total immersion in lava), so the only way you're going to get your action's worth is if you bull rushed them into a Sphere of Annihilation. In all cases, using it with the DM's help basically involves increasing the distance they're going by using falling. Specializing in it is a waste of feats, since even with an accommodating DM, the number of times you're going to find this relevant is likely 1/5 encounters. Not specializing means you even bite an AoO right back for even daring to try.
Disarm - Attack action, you can do it with an AoO, or your later iteratives. It needs to be as valuable as the damage and to hit of one of these. This is attainable, but situational. If the enemy requires a weapon, disarming them castrates their combat ability and they'd need a fallback via quick draw etc. The limiting factor here is the investment. You need Int 13(not hard, but counter to a fighter's main strength) and two feats to avoid the AoO, which renders the strategy useless. If you didn't need two feats just to use it, then it could do some good, due to being situationally effective. It is indeed comparable to a straight out attack, but not applicable to enough enemies unless its a city campaign or something.
Feint - Standard or Move action, so with the feat, you can use it with an attack. Success rate is generally high, few monsters have any Sense Motive to speak of(even after adding BAB), and skills are easy to raise. The cost is your further iteratives and extra attacks. For a rogue, this is reasonably effective, if you can't get a flank, just feint and attack to get your sneak attack in. For anyone else, its not really that useful. To expand the usebility you can allow this to make the enemy flatfooted for real(which has perks in avoiding AoOs), perhaps with a feat investment.
Grapple - An attack action, which is cool, but the cost is YOU are grappled as well, losing a lot of your stuff. In fact, Grapple is the only combat maneuver to put you in a worse situation than when you started if you succeed. This added to the multitude to steps, rather limits its effectiveness. Added to that, given it's benefits, you'd want to grapple spellcasters(but have to contend with freedom of movement or no somatic component teleports, which is ok, this is a spells being too strong issue) and powerful solo threats. Powerful solo threats are going to totally punk your grapple checks to start with, and for large ones you can't even start to grapple them back. If you use the example of grappling the frenzied berserker until they calm down. Do you even realize how high the difficulty of grappling a strength focused character, with massive AoO damage and accuracy is?
So to sum it up, Grapple is a clusterfuck. It can be useful, except it screws you exactly as hard as it screws the other guy.
Overrun - Standard action as part of a movement. This puts it in the same ranks as a full attack. Needless to say, moving, provoking AoOs multiple times(for leaving a threatened square and for performing the move to begin with) and then MAYBE knocking over one opponent would find it hard to compare with even a single attack, if that attack was your last iterative you had a maybe a 30% chance to hit on.
Sunder - Largely the same as Disarm, except disarm does it in one hit, so its already behind schedule. Next you're destroying equipment, which reduces your encounter loot. Most commonly destroyed equipment is weapon(since you can't break anything else for the most part) which is also the single most valuable piece of equipment. Yes, sure the DM can make up the lost value later, but tracking party WBL is hideously time consuming to begin with. The most common methods I find are to simply deliver average encounter wealth, or to just tally wealth expected and deduct random loot off it. You can't use total party wealth, because the random loot tables give you more money than the WBL table for a reason, expendables. Thats ok, except again, you're destroying the weapon, you know, the loot aimed at you, the weapon using guy. In either case, it does the same thing as disarm, except it requires more hits to break a given item, and when it breaks its less favorable than simply disarming.
Trip - Attack action, you can do it with an AoO, or your later iteratives. So at a minimum it needs to be as valuable as the damage and to hit of one of these. This is attainable, as long as the enemy can be tripped at all, as the resulting speed decrease is still good, and they set themselves up to provoke more attacks. With investment, you even get your sacrificed attack back, so you can use it as a major part of your day. There is a risk of counter tripping, but using a weapon to trip(theres several fine reach trippers) and picking your targets will reduce the danger.