It was brought up that there's no set explanation for why low tier classes are generally less effective. With that in mind, I figured I'd start one. I'll be doing one for each tiers, but I want to get the low tiers out of the way first, because most people know why classes like Wizards and Druids are above average. I'm looking for your input on the classes, and to make this a guide for people new to CO. Thanks to all who contribute in advance.
From JaronK's Tier System For Classes guide, the widely accepted Char Op base power description thread:
Tier 6: Not even capable of shining in their own area of expertise. DMs will need to work hard to make encounters that this sort of character can contribute in with their mechanical abilities. Will often feel worthless unless the character is seriously powergamed beyond belief, and even then won't be terribly impressive. Needs to fight enemies of lower than normal CR. Class is often completely unsynergized or with almost no abilities of merit. Avoid allowing PCs to play these characters.
Examples: CW Samurai, Aristocrat, Warrior, Commoner, Divine Mind (before Mind's Eye updates)
Why Tier 6s are Tier 6:
CW Samurai
[spoiler]
Cons:Pros: It has full BAB, d10 HD & good Fortitude-save. It also has Sense Motive and Diplomacy in class as notable advantages over Fighter. It also has few bonus feats and one class feature in Mass/Improved Staredown; being able to Intimidate multiple creatures with one move action and at range is actually kinda useful (if you didn't need the actions to...y'know, full attack). Oh, and he has Smite which is still usable...once per day most of the time.
Seriously, the absolute best thing about this class is that you can fall after level 11 to become an Ex-Samurai 1/Ronin 10 with actual class features! -Eldariel
-------------------------------------------------
I like the samurai's Staredown ability, since it gives a different attack option than simply DMG and AC. A 14th level samurai can intimidate 2/R (double move action), or 3/R with a Belt of battle (MIC), so in 1 round he can send all opponents within 30ft to frightened or panicked. Zhentarim Fighter does this better, but it's a web enhancement to a campaign-specific book, so it won't always be available to PCs.
Samurai 10 with the Fearsome Armor enhancement (DoTU) and the Imperious Command feat can do the double intimidate 4 levels sooner than normal, and send foes cowering for 1 round first. Of course, at that level a Zhentarim fighter with that armor can do a triple intimidate, but whatever.
The samurai is better than the NPC Warrior class - it actually has class features and a higher HD. Even if you break the code of honor (which is simple: don't be dishonorable or chaotic), all you lose are the Cha-based class features, so you would still keep Improved Initiative, etc. You could even be LE and just strive to be evil without being dishonorable, like Lord Soth or something.
Decent prestige classes for the samurai:
Exotic Weapon Master: 1 level gets the Exotic Blow ability, which is very solid PA damage.
Ronin: Mentioned earlier.
Kensai: The Samurai is one of the few classes with all Kensai class skills, and the oath of service meshes well with the samurai's vow. It's not THAT exciting, but it is a very flavorful class, and choosing your own weapon enhancements is a lot of fun. Also, you can return to Samurai after completing kensai (But why would you??)
Knight Protector: This will make you more of a tank, though none of the features are awesome (as a sidenote, you gain Tower Shield proficiency without knowing any other shields! Weird, huh?). Also, you can return to Samurai after completing Knight Protector (But why would you??)
Knight of the Iron Glacier (FB): C'mon. It already requires EWP: Bastard Sword, and you KNOW you want to ride a giant rhinoceros!
Bloodstorm Blade (TOB): First, it requires MCing into warblade, which is better than samurai. Second, it will let you change your EWP: Bastard Sword to any other weapon - and the same should apply to your other subpar feats that specify only a bastard sword and short sword. Besides, throwing weapons as a full melee attack is just awesome. -Akalsaris
[/spoiler]
Aristocrat:
[spoiler]
Cons: It has a slightly worse frame than a Druid, Binder, or Cleric (lacking the good Fort save)... but it has no class features, spells etc. whatsoever. Nada. And the high starting gold doesn't matter if you start higher than level 1. -Agita
Pros: It gets the highest starting gold of all classes (4d8x10 gp), and it has average basic stats (Medium BAB, good Will save, d8 hit dice). Has Diplomacy and all synergy-relevant skills as class skills, so it can be a mean diplomancer in a NPC class-only campaign. -Agita
[/spoiler]
Warrior:
[spoiler]
Cons: No class features, only a d8 hit dice, worst set of class skills in the game -Ninjarabbit
Pros: Full BAB and proficient with martial weapons and all armors and shields -Ninjarabbit
----------------------------------------------
If you want to play as an ex-paladin, you can't advance in the class any further. Levels in warrior will advance you just as if you had taken more levels of ex-paladin. -The_Mad_Linguist
----------------------------------------------
One pro for the Warrior is that if you build him as a charger, you can very easily be strong enough to take out enemies above your CR. Something like Orc Warrior with Power Attack, Improved Bull Rush, Shock Trooper, Mounted Combat, Ride By Attack, Spirited Charge, and Headlong Rush, riding any random flying creature, with a Valorous Lance... you should have little trouble doing 350+ damage per hit by level 20. If you want to try and actually look powerful as an NPC class, and it's a very combat heavy campaign, the Warrior can get the job done. -JaronK
[/spoiler]
Commoner:
[spoiler]
Cons: d4 hit dice, poor BAB, poor saves, no class features, only proficent in one simple weapon. -Ninjarabbit
Pros: Ummm....ummmm...... oh yeah it can qualify for the Survivor PrC after level 1 and can take the chicken-infested flaw, has spot and listen as class skill so it's better than the fighter in that respect. -Ninjarabbit
[/spoiler]
Divine Mind (before Mind's Eye updates):
[spoiler]
Cons: Aristocrat with Mercantile feat, is better and more versatile. That's all you need to beat it. Half way to Paladin's roleplaying restrictions, and bad flavor combo with psi. Worst "spell" access in the game. Very bad "spell" list until around 10th level, and possibly useless on some levels before that. Auras are the main class feature and they are almost not an aura at the start. Some auras are useless before 10th level. Psi-focus vs Expend Psi-focus problems are a possible bad combo early on. A CO-built and run Wizard 2 can probably beat any Divine Mind build that isn't an Initiative build. Ouch. -Awaken DM Golem
Pros:
Divine Mind can have Epic Spells at level 30, the same level it gets Free Aura switching. Might be a difficult BBEG for level 15 delayed casters (not 8s). See the Mind's Eye and all the Psi stuff, other psi-classes aren't supposed to use , and you have a Tier 5 or better. Even a Divine Mind can do a pun-pun + pazuzu power up, just not right away. -Awaken DM Golem[/spoiler]