Picking your class: A general guide

Credit to Jaghatai from official forum

*The following guide includes opinions and personal experience of the poster. If you have a problem with that, I dont care. Most of it applies regardless of opinion anyway*

The Beginning of the Journey

You just installed 9Dragons, eager to get on with the fighting, casting and conquering the world. I will assume you already know which clan you intend to play, because that is enough for a whole different guide on its own. Up until Opening Chi 1 (Level 25 for those not familiar to the games level system) you are playing a Vagabond, the basic melee class in the game, with (at best) access to the Basic clan techniques, and the first "Smashing" skills.
By Opening Chi 1, its time to do a quest, and pick your class. Until then, just familiarize yourself with the game. No decision aside from gender, looks and clan affiliation will matter past OC1. Stats, most skills and masteries will reset either way.

Definitions: The classes themselves: What is what?

Every clan has the same 4 classes. They do go by different names, obviously, but again that is clan choice territory, and I wont touch on that here. It is enough to know that the differences between the same class of a different clan are minor, and generally not worth noticing. I will touch upon that later either way.

The Warrior

The Warrior class is, by far, the most numerous one in 9Dragons. Basically, you can expect 75% of all players to play Warriors. The Warrior class is the only class able to use a Clans primary weapon (Saber, Sword, Polearm, Wheels, Staff or Spear), has he highest damaging basic attacks (except for axes, more on that later) and a large number of high-damage smashing attacks with added conditions. Due to the nature of the class, you can advance far faster than the other classes since you dont need to work on skills a lot. Your mainstay skills level as you fight, and the others usually arent worth training specifically. That makes the warrior the lowest-maintenance, easiest and most comfortable class for someone looking for fast advancement.
Also, in current PvP combat, warriors are probably the strongest class in the hands of average players. While a fully skill-leveld nuker with a good player behind it can wreak havoc on you, or a hybrid can be frustratingly resilient and eventually outlast you, on average PvP is the area of warriors.
In PvE, warriors do very good damage, but rely on other classes for buffs (that become extremely strong towards the mid- to endlevels) and healing/wound recovery.
Play a warrior if you like fast progress, little complexity, high PvP potential and dont mind being expendable in the current market of players, as there are so many around.

The Nuker

The Nuker class is a rather rare breed. It is the only class without a real combat style, thus lacking the flashy animations and moves of the other classes. Combined with very limited graphical effects of the Chi Kung attacks, this makes for a visually very one-sided class. However, under the somewhat bland skin lies a vast potential of power. If you play a nuker, prepare to spend some effort to level up your skills outside combat. Simply grinding out exp will NOT raise your skills enough in the later levels. But once you have a decent level in your spells, the class starts to shine brightly.
The damage-per-skill becomes downright insane at higher levels. Basically, you can 2 or 3-shot experience-giving mobs in several cases, while never getting hit if you play well. For sheer soloing power, most builds (aside from the 250 STR build somewhere else on these boards) little can beat a nuker that knows how to pick his fights. The fact that you do not need to move much further makes the gameplay comfortable, if repetitive.
Play a nuker if you like long range, massive firepower, and a steady, unchanging playing style. You will be rare, and get into groups decently well since you add a lot of "low maintenance" damage, meaning you dont require effort from healers, and not many buffs.

The Hybrid

Ah, the hybrid. In 9Dragons, in comparison to other games, picking a hybrid doesnt mean you pick a basically 2nd rate class in all regards. The hybrid is the main class for using the secondary weapon of each clan (Fist Weapons, Axes, Daggers). This class is about the only true solo class at the very high levels. Your buffs and heals may be outclassed by the Buffer/Healer class, but that doesnt mean they are useless. The Chi Kung attacks will usually be for pulling, rather than doing damage, but they offer the best way of picking your fights..... the fights come to you. In groups, you are usually going to do some buffing, and then play tank, healing yourself and possible nearby players off and on. You are something of a support to the healer/buffer in that regard. Hybrids are the second most numerous class currently, and share the weapon type with the healer/buffer of their clan. In PvP, they are the best class to play if you want to show warriors their place, but require much practice and good grasp of the class mechanics for that.
You will spend quite some time levelling your skills outside combat, too. Unlike the warrior, you dont rely just on your fighting techniques, so dont pick this class if you dislike the thought of training skills.
Play a Hybrid if you like versatility, the secondary weapons, and the ability to solo and tank just about anything that gives exp and isnt deep red. Expect to spend quite some time working on your skills, and dont expect exceptional treatment in groups. Its a good allround class for someone who doesnt favor one area of the game over the other.

The Healer/Buffer

First of all, this is where 9Dragons moves away drastically from other MMORPGs featuring the tank/heal mechanic. The 9D healer is not a healer in the traditional sense, and is not supposed to heal a party while staring at health bars. And incidentially, the class is not able to do that. So, forget for a moment what your priest/cleric/monk did in your previous game, and read on.
The Healer class is the true support class, and primarily, through BUFFS. Your buffs, if leveled up, are second to none, and make a big difference. Actually, they are sorely needed to get the best exp/hour. So, if you mind buffing people, this class will probably not be for you.
The healing aspect is a totally different beast. The heals are mostly Heal-over-time spells, and touch range. The latter fact makes it virtually impossible to heal an entire group that doesnt stand close together. It also means you WILL draw unwanted attention of the mobs, because you basically run into the fray. Also, heals arrive slowly, level slowly, and heal slowly.... only at the very end of your skill selection are there direct heals, and the only true heal in the eyes of a mainstream MMO player is on a 30 minute cooldown, making it more of an emergency button.
There are extremely few healers around, partially due to the fact that you will spend a LOT of time levelling your skills. Almost all skills you raise just by fighting arent important to the class, and attributes almost exclusively matter for fighting. The Buffs and Heals are all a matter of levelld skills, so the class plays very high-maintenance.
BUT, you will be loved by groups. You will be invited all the time, asked to buff by about everyone who recognizes your class, and in general be bugged about rezzes, buffs, heals and help 24/7. If you like attention, and teamplay, this is the class for you. Dont expect to get much quiet, or solo later on.

Tiny things to consider

A few things facts that are of minor interest still exist.
First, there is a difference between the warriors between the clans. There are clan specific skills, though not gamebreaking, that add a little flavor. For example, the Brotherhood of Thieves has a defensive buff that isnt shared by Heavenly Demon. Also, the weapons are not the same. While everyone receives new combat styles at the same levels, the weapons and the actual fighting style effects are different. For example, a warrior of the Shaolin will do more damage per hit than a Sacred Flower Mistress of War.
Second, the last big heal of the Healer class differs. Some clans receive the aforementioned emergency heal, others receive different abilities. While it would take too much time discussing the pros and cons of each clan, be assured that NONE of these clan-specific abilities change the basic ways of how the classes work, nor is a HD warrior better than a BoT warrior by default.
Third, I did not list the Vagabond. While technically its a class on its own, it has no place in the high-end balance of classes, and should be regarded as a warrior in most regards.