If you aren't sure which cultivation you would like to complete on your class and want some informed opinions this is the place for you. Below I will explain the benefits of each cultivation for all the classes.
BarbarianSageOk so for barbs sage is in most circumstances better for tanking and as such is used for almost every catapult pulling barb in existence, the sage squad buffs give more attack and more hp than their demon counterpart. The sage barb also has more physical defense in tiger form. Basically if you don't want to die ever and are happy to relinquish most of your ability to do damage aside from armageddon sage is the choice for you.
Demon Demon barbs are excellent at dishing out tons of damage. Demon barbs have a spammable +35% crit rate with bestial onslaught, a more reliable stun and also dont sacrifice any damage by going into kitty form. If you want to be a panda who can kill things you want to go demon. On a side note demon roar is excellent for killing melee attackers in the pk events held within the lost city arena or in TW/Cube but don't be fooled, the bramble like a veno's doesn't work in the open map pk.
VenomancersSageSage veno's for the most fill the support but like all sage casters have a high damage potential. Sage amplify has a more substantial damage increase. Sage veno's though are mostly chosen because of their ability to instantly purify themselves and because that their purge becomes an aoe.
DemonDemon veno's are potent damage dealers and excel in killing both single and multiple targets. Their primary attack has a wood defense debuff, their ironwood scarab while not as consistent can reduce and enemies pdef to 0. How ever the primary reason demon veno's do more damage is that their Parasitic nova has a 2/3 chance to put a HF effect on the target increasing damage dealt to them by 30%. Demon summer spring also offers great utility giving the veno a short anti stun which stacks very well with one of the veno's 79 skills which is like a second ironguard.
WizardsSageSage wiz have alot of damage potential, their divine pyrogram give an additional fire debuff, glacial snare has an additional water defense debuff and their black ice dragon (BIDS) gives a significant crit bonus proc, sages also have a higher base magic attack, how ever they sacrifice alot of physical defense and therefore survivability for these small damage bonuses. Sage force of will becomes an AOE, even if its range is tiny.
DemonDemon wizards are broken strong. Their earth shell gives an extra 50% pdef (exactly what you want on a caster class) Three of their main damage skills have decreased casting time, Mountain seize has increased range which grants increased utility on the stun. Demon force of will has a faster cooldown by two seconds which is also very very useful in 1v1 and group pk situations, stone rain grants a 20% chance for a 5 second stun, while this seems like a gamble if used properly it can be a huge advantage in any PK situation.
BlademasterSageSage BM's main advantage is the increased pdef from bell, the greater base damage with fists and potentially the higher % swings on marrow usage, how ever this marrow buff can be a double negative if used incorrectly it can make the BM an easy target. Sage cyclone heal provides a 5 second buff on the duration of the attack speed buff.
DemonDemon BM's are more of a threat to anyone than sage bms for a few reasons, Demon bell spam provides an insane pdef increase. Demon HF has a much longer duration which is a huge benefit for group pk. Demon drakes breathe bash has increased stun duration and demon roar of the pride never misses (excluding tidal protection and anti stun. Demon BM's marrows also sacrifice less of the defense so a BM can gladly magic marrow and demon bell and not become squishy to sins/ea's.
AssassinsSageTidal. Sage tidal. 66% chance to evade negative status effects. Its OP. Its annoying and i hate trying to deal with it when playing my wizard. Other benefits include perma Wolf emblem for increased crit damage constantly and inner harmony having a 30% chance to grant 3 sparks. Maze steps lasts for longer, ribstrike has a 10% hp debuff for a short time and tackling slash has a much longer duration than demons. +5 attack levels on chill of the deep. Subsea amps for 66% instead of 33%.
DemonStuns. All the stuns. Headhunt lasts longer, tele stun last longer. Stealth has a shorter cooldown. Wolf emblem crits for 40% extra damage, with these three skills considered demon sins imo have the potential to melt anyone almost instantly, what they lose in with the tidal and subsea difference is made up for in sheer damage output. Subsea lasts for alot longer. Thats about all to say about sins really.
PsySageJust tanks. Psy will lasts longer. Bubble of life is an aoe purify. The main aoe's are better. They can drain chi from your opponent using primary fast channeling skills. Its a psy though. Its going to be be annoying and OP no matter what cultivation.
DemonCrit damage. Landslide proc gives a psy a crit buff. Thats the last thing you want to see. A high damage mage who casts fast with a high crit chance. Otherwise usual stuff, OP psy etcetc.
ArcherSageIncreased base damage, increased range, increased damage on magic skills, another magic damage skill, BOA for tw is nice, longer stun, more take aim damage, wingspan gives 20% for 100 chi. STA 20% HP debuff. Hax.
DemonQuickshot proc is the only reason peope ever pick demon archers. Faster attacks = more likely to purge=faster kill.
ClericSageStronger heals, faster CD purify, longer lasting debuffs. Cleric is a cleric though. All you gotta do is buff and spam heal. Large range on the aoe heal is nice.
DemonMetal mages, only pick if you wanna be dum and try kill people with cleric. huahuahua
MysticSageLook. I can't see why you would ever do this (change mantus ;p), but if you WERE to do it here is why you would want to. Verdant shell gives 10% more pdef, break in the clouds can purify you, the primary attack that you spam has a 20% chance to give you a little bit of chi and energy leech antistun lasts a little longer, imo sage mystics are a defensive option.
Demonok, so demon mystics are better than sage in every way and this is why. Their thicket its better, has the chance to hf if im not mistaken. Rapid growth lasts longer, great for getting off combo's, the knock back hits further (its not a lot but it is enough). More chi from the spam healing which mystics love to do when getting attacked. The AOE heal has a chance to purify. Falling petals lasts for an age. Useful for group pk, better gale force, more stun more kill huehue.
SeekerSageMore damage. More defense. :|
DemonNo, only for wanna be bms who are gunna try spark and auto attack people with duel edges, for occult ice using nooblords only.
My picks (mine not yours don't rage about it.)Barbarian Demon for pk.
Veno Demon again.
Wizzy Demon..
BM Demon.
Sin Sage
Psy Sage.
Archer Sage.
Cleric Sage.
Mystic Demon.
Seeker Sage.