Paths of the Righteous is pretty awesome.
It's full of PrCs from followers of good gods, and most of them could be worth taking.
It starts with two feats. One is meh, but it's a prerequisite for the second which is amazing.
First, Favored Prestige Class:
Benefit: Choose one prestige class and one skill that is a class skill for that prestige class. Whenever you gain a level in that prestige class, you receive +1 hit point or +1 skill rank. You gain a +2 bonus on checks using the skill you chose from that prestige class’s class skills. If you have 10 or more ranks in one of these skills, the bonus increases to +4 for that skill. This bonus stacks with the bonus granted by Skill Focus, but does not stack with a bonus granted by any other feat (such as Magical Aptitude or Persuasive).
The choice of favored prestige class cannot be changed once you make it. Levels in a favored prestige class are not the same as levels in a regular favored class, and as such levels in a favored prestige class can never be used to qualify or gain favored class options like those introduced in Pathfinder RPG Advanced Player’s Guide. You can have only one favored prestige class, but can still have a favored base class as well.
You can select this feat before you gain levels in your chosen favored prestige class, but the benefits of the feat do not apply until you actually gain at least 1 level in that prestige class.
Then, Prestigious Spellcaster:
Prerequisite: Favored Prestige Class with selected prestige class.
Benefit: The first time you gain a level in your favored prestige class and the spells per day class feature does not grant an increase in effective level for the purpose of casting spells, you gain new spells per day as if the prestige class did grant +1 level of spellcasting for that level. This effect is retroactive if you gain this feat at a level beyond the point where your favored prestige class would normally have not advanced your spellcasting.
The Prestigious Spellcaster feat does not have any effect if your favored prestige class does not have the spells per day class feature, or if it does have the spells per day class feature but already grants a level increase for every level of the prestige class (as do the arcane trickster and loremaster prestige classes).
Special: You can select the Prestigious Spellcaster feat multiple times. Each time you select the Prestigious Spellcaster feat, your effective caster level increases by 1. However, regardless of the number of times you choose this feat, the total increase to your effective caster level cannot exceed your actual prestige class level.
This feat also applies to prestige classes that grant extracts per day instead of spells per day.
So, that just made a few dozen PrCs viable.
Then, the PrCs: (If you want to know more about any of these, just ask.)
Ashavic dancer: Easy entrance, 9/10 casting, some mediocre bardic music effects, ignore undead mind-affecting immunity and versatile performance. It's decent, worth it in the right campaign.
Brewkeeper: Easy entrance, 9/10 casting, turn spells into potions that last 24 hours, free metamagic up to 3+class level levels/day, debuffs on touch spells or splash weapons, and can use own CL for potions. One of the best in the book. Take accelerated drinker or potion glutton and you can buff yourself without spending your standard action.
Crimson templar: Full BaB, 3d6 Sneak attack, three bonus feats, some flight and fire resistance, bonuses against evil outsiders. Pretty powerful for a martial character, if you are going to fight a lot of evil outsiders, it's great.
Darechaser: Easy entrance, Full BaB, Adrenaline rush gives skill bonuses +more at higher levels, can add a bonus exploding die to d20 rolls, if that die makes the difference, gets a minor bonus. Not that great.
Dawnflower anchorite: Easy entrance, 9/10 casting, bonus to attack and damage against evil creatures, can advance most divine class features, other minor buffs. If you enter this as a cleric, you don't have to lose anything. It's pretty great.
Devoted Muse: Full BaB, Cha-to-AC (up to level), Deeds, Panache, Feint can apply debuffs, bonuses when attacking targets debuffed by feints. Generally does a swashbuckler's schtick better than the swashbuckler.
Heritor knight: Full BaB, advances weapon training, Cha to Will saves, a number of nice standard action attacks that work with vital strike, Touch to heal or harm and stagger, and constant air walk. Pretty nice for a fighter.
Hinterlander: 9/10 casting, Favored enemy w/added benefit, Three bonus archery feats, bonuses in wilderness, and Imbue Arrow. Quite good for a Cleric Archer.
Rose warden: Easy entrance, 5d6 sneak attack, can gain 5 rogue talents/advanced talents, Freedom of movement, bonuses in cities, and a buffed sneak attack against evil or lawful enemies. Quite good for a chained rogue, still decent for an unchained one.
Runeguard: Easy entrance, 9/10 casting, a bunch of runes with decent effects (1 free level of metamagic, imbue friends with abjuration spells, negative energy immunity, and all-day telepathic bond). The effects are minor, but it's still worthwhile for a wizard.
Sacred sentinel: Full BaB, advances animal companion and some other abilities, and a bunch of not-great defensive abilities. It's pretty meh, I don't really see it getting used.
Scar Seeker: Easy entrance, Full BaB, 5/10 casting, scars give kinda masochistic buffs, advances Lay on hands and Smite. Not bad for a Paladin.
Sphere singer: 9/10 casting, 6 skills/level, decent bardic music, versatile Performance, ends up turning you into a fey with some nice buffs. Nice if you want a skilled caster.
Stargazer: Easy entrance, 10/10 casting, grants and advances familiar, two hexes, Stars subdomain, Coat of many stars and Star chart revelations, other minor buffs. This is
awesome. It is pretty much a straight upgrade for a wizard. There's really no reason not to take it.
Other stuff:
Shield of wings is a divine spell that combines fly and resist energy (fire), still 3rd level. Probably better than Fly for them.
Flame Blade Dervish feat give Cha to damage with Flame Blade, penetrates fire resistance. If you want an oracle that fights with Flame Blade, now you can do that.
Bladed Brush feat makes glaives finesseable, lets you use it with precise strike or spell combat, can fight as if it doesn't have reach. Quite nice for magi.
Erastil's Blessing feat is Zen archery for bows, requires Weapon Focus (longbow). The cleric archer is back with a vengeance.
Uncanny ally feat give adjacent allies the benefits of your uncanny dodge.
Smite Evil Magic feat lets you spend a use of smite evil to use spell sunder against anything made by an evil creature.
This had the highest gems-to-chaff ratio I've seen in a Pathfinder product yet.
