Cleric.
In top1, Cleric.
In the top2 expansion - Seal master.
As someone told me the other day.
After a certain threshold level, and when you reach 130, some clases that weren't start to get more "hax" for no reason other than the extra stat and skill points, and get to a stupidly ridiculous development where the ones with more skill diversity or uniqueness have the advantage, switching for example importance of Hp, con and def to only "who gets to cripple the other's Movement Speed first wins" because as Individual units they are as OP as they can be, so importance switches from plain stat numbers to special effects to win. Seal masters Excel at that, but in TOP1 Get a max-leveled cleric fully gemmed and with all focused on SPR stat, 110%, Black Dragon Energy Shield, boost her with I.M. if you want to get crazier, and that could one-shot characters, or almost. Take down champs by small chunks of HP at a time while running, 2 hit or 3-hit crusaders at the same level if they are full of BD Heart gems in gloves or boots.
Level 80 max skill points are rather limited for Herbalist classes. It's like they are half-baked characters, while Crusaders have everything level 10 and Voyagers too, if it's for their main skills they use on land. At "low levels" Clerics don't have the stubborness to die of having a full con build while the Seal Masters get increasing returns for each extra point they put in SPR and in maxing their seals or skills, or buffs if they are free, increasing offensive capabilities that weren't there before. A lv 130 cleric, in my opinion, might not win against a lv 130 seal master. But a lv 80 cleric, will win against a lv 80 seal master. And against crusaders, and champions, easy kills, and voyagers more or less too due to the magical def and energy shield being a cushion that improves by gear symbiotically. Sharpshooters may be the most dangerous to a Cleric, still, but only if they haven't been killed first by some slash or a breeze of wind before reaching the target. Stop their movement speed or get as fast as them, and the disadvantage fades away.
So Cleric. Or so they told in the stories of who is the better Forsaken City class as well, or easiest class to solo-level up.
All of this is solo player though. If you have some friend, and make a duo, a Seal master-Sharpshooter combo is deadly (Only at high end level) and may be the only one to be able to handle large groups of dispersed people at once due to cooperation. Only if the seal master is equipped with the same movement speed as the sharpshooter, and both keep confusing and running around at olympic speeds, like say, 700 mv.speed, sealing one and attacking the other, while the one who sealed puts a debuff on the ground behind the one who attacks, switching and casting recover on the debuffs of the other. When people come to kill, 2 working together are like 4 people individually though. Sealing the sealers who come to seal the sealer, or unsealing the sealed attacker if the sealer wasn't targeted, being insta-recovered both in their PvP scenario. The rambo friends.
If you have 2 more friends and play as 3, or 4, 5, etc... Coordination wins against bare numbers, if it is not messy. If you go to BD lair and find a group or 30, kiss goodbye to your life. You have 15 mouse clicks aiming your character textures with an Illusion Slash, 7 with Enfeebles, and 7 with Cripples. And 1 guy with a flash bomb, just in case you happened to make it through. Stats alone don't win wars, "special effects" yes, if you are still alive enough.