People tend to regard the Champion as the only consistently good combat spirit for a Medium, but I think that's because they're overlooking the ability at level 11 to use it twice on one round to boost both attack/damage and saves for the entire party, at higher bonuses than what a (base, not tricked out) Bard can do.
Inspiring Call (Intermediate, Su): As a standard action, you can grant all allies who can see and hear you a competence bonus equal to your spirit bonus on either saving throws or attack and damage rolls. You choose which bonus to grant each time you use inspiring call. This ability lasts for 1 round. If you have the decisive strike greater spirit power, you can use inspiring call as a move action. If you have the legendary marshal supreme spirit power, you can use inspiring call as a swift action.
It seems like at 11th level you can use both your standard to boost attack/damage and your move action to boost saves. There's no stacking issue, and there's no rule I can think of to prevent you from using the same ability more than once in a round if you have enough actions. Am I wrong?
Note that this would give +3 bonus to everything at 11th when you can first pull it off, +4 at 12th, and of course you can get an extra +1 with the Spirit Focus (Marshal) feat, up to +2 more if you're a Fiend Keeper who blew a full round action to buff up. Not too shabby as party support, even before you toss a 1d8+(3-7) Spirit Surge once per round to help out a save or critical attack that somehow failed even with those bonuses.