Marshals are good faces, no question: 4+Int skill points, pretty much all the key skills, high Charisma and the option to double said bonus. With Motivate Strength, they can be a decent tripper; with Motivate Charisma they can do a solid Intimidate build. Heck, you could probably do a decent Knowledge Devotion archer build, even-- Charming the Arrow, Motivate Int, Motivate Ardor or Steady Hand... Cha to Dex can help you with the sneaking, they get good weapons and armor and almost a full BAB... they're not fantastic at anything, they don't really have the feats to specialize in more than one thing, but they're a decent (if boring) enough base and all-arounder that I'd feel comfortable putting them at Tier 4.

Divine Minds... I admit that I've never seen one in play, but they're certainly not T6 trash, especially if we assume the Mind's Eye upgrades are around. The Auras aren't great, but they aren't nothing; Perception is always useful to have around, and Attack gets you back to about a full BAB. You get Turn Undead via ACF; you get manifesting that's... probably around Paladin/Ranger level; your get slightly higher levels and it's easier to buy more power points, but you don't get unique low-level powers like they do. It's probably somewhere around the T4/T5 level. It starts damn low (you're basically a Warrior at 1st level), but unlike a lot of low-tier classes I think it picks up at higher levels instead of fading. Call it Tier 5, maybe even 4.5.

Dragon Shamans are bad. They can deliver a stacked metabreath nuke, but so can any class who's a Dragonborn. They don't get the bonuses to use a weapon, they don't get a strong enough breath weapon to rely on it, they can't do much healing, they can't do much in the way of skills... Tier 5, and low in the tier.