I guess these ten are my top favorites.
#10 Martial Discipline(ToB, +1) Gives an additional +3 to attack rolls while using a ToB stance.
#9 Warning(MiC, +1): +5 insight to Initiative.
#8 Splitting(CoR, +3, ranged): Clones any arrow shot out of your bow. I do mean any, even special save or die arrows for example.
#7 Command(DotF, +2): +4 Competence to Charisma, Competence holy crap.
#6 Empyreal(BoED, +2, armor): Like defending but for saves and is a Sacred bonus type. Source of the +6 to saves for 64k.
#5 Fearsome(DotU, +5,000, armor): +5 Enhancement to Intimidate and you can Demoralize as a Move Action for Fear based lock down.
#4 Necromantic(HoB, +3,000, ranged): Animates up to 20HD of undead within 60ft for ten rounds, all of which are under your control.
#3 Wrathful Healing(E&A, +3): Heal half the damage you deal.
#2 Energy Drain(DoF, +2 armor/shield): Shield Bash or Unarmed Attack(armors only) deals 1d4 negative levels.
#1 Valorous(UE, +1): x2 damage while charging, virtually everyone can use this. Even spellcasters (hold a touch attack then charge).