Fighter, Priest and Cipher are definitely the most powerful classes. These carry a group and if you don't use them, you'll be making it a lot harder on yourself.
After that, I'd say you have classes like the Rogue, Ranger, Wizard (although later on they become really good), Chanter and Druid. These classes are pretty alright and nice to have, but won't have a large impact if you swap them out between each other. They all have really good damage, support or a combination of both.
Following those are the Barbarian and Monk. You'll be putting more strain on yourself if you want to play these classes (far more micromanaging), but it's certainly doable. Still, it's far easier to just use any of the above classes.
On the last spot I'd place the Paladin, sadly just about any class can replace the Paladin and do it better. The higher level they get, the more 'meh' they become. They are basically a weak fighter combined with an extremely weak priest. The most common brought up defense when it comes to Paladins is, "I managed to finish the game with a Paladin in my group". That's not really a gauge to measure how good a class is though, especially not when people are finishing the game with just one or two party members. There is no good reason to bring a Paladin to a group, apart from simply wanting a Paladin in your group.
To quote myself on Paladins;
Paladins are lackluster. They lack any and all focus, I say this as someone that finished the game on Hard difficulty with a PC that was a Paladin.
They're worthless tanks compared to fighters, but so is anyone else really. Fighters have far more defenses, more engagement and better endurance recovery (in more than one way). A Paladin is only on equal footing when it comes to an initial deflection bonus and is far more of use to assist other tanks. This is only reinforced due to the fact that some of the powerful defensive abilities a Paladin possesses only affect his allies and not the Paladin himself.
Damage wise they're alright for short fights and when you can rest occasionally (to regain Sworn Enemy), but they quickly run out of gas during long fights. Where other classes gain more tricks in their bags to use for long fights, we're still stuck with the initial 2/encounter Flames of Devotion at level 12. This, despite being able to heavily specialize and improve this ability along the way.
Then there's support. In this category Paladins also tend to fall short. The range of aura's is tiny and requires a hefty investment in intellect to even properly cover allies in melee. Boots of Zealous command are almost mandatory for any Paladin to take, simply to make aura's worthwhile for anyone but the Paladin and the people almost literally hugging him. The other supportive abilities that Paladins are able to obtain are decent, especially the ones later on, but a Priest basically brings the same utility and much, much more.
Once you've tried out the other classes, the Paladin just feels so lackluster. Another way to gauge their shortcomings is that during my playthrough(s), I never felt "next time I level up my Paladin, it'll make a big difference for the group" while with other classes like fighters, ciphers, wizard (later on) and priests I felt the opposite. They're alright offtanks, but the same can be said about most classes when you stick them in plate armor along with a bit of perception or resolve.
At the moment I would say that the only real reason to get a Paladin in your party, is if you simply want a Paladin in your party.
Edited by eubatham, 06 April 2015 - 06:37 AM.