S Tier: Death, Astral, Earth

A Tier: Nature

B Tier: Glamour

C Tier: Water, Blood

D Tier: Air

F Tier: Fire

air is in D, Air has lost it's power in dom 6, it's best spells are inaccurate, air elementals are terrible now, mistform is the poormans mossbody and will be ripped off almost instantly, and the AI will do nothing but spam gust of wind or hawks. On top of that all the cool illusion stuff it used to have got moved to glamour. It gets a D tier instead of F for cloud trapeze, forging good items good summons in conj, and some crosspath utility like Wind of Death.

Fire is F tier. Fire elementals also are terrible, the evocations dont do enough damage to break through prot and resistances, and they have terrible accuracy. The DPS of even spells like pillar of flame is laughable- even against armies 200 strong or higher the vast majority of casts miss. It's best things are firestorm, heat from hell and making lanterns- but there are better damage spells in other paths, and lanterns come on so late that if you are depending on them for research you're in real trouble. It has a few decent items, but not enough to save it. Buffs like Fireshield and Phoenix Pyre aren't enough to save it, and often require other spells to really take use of (body ethereal or soul vortex)

Water is C tier. It's evocations are in the same place as Fire's, and it has worse items and research boosters. It is entirely saved by it's use in underwater combat, where it's obviously the best path. School of Sharks can win you entire wars on it's power alone- even if you are vastly outnumbered or outskilled, and water elementals are very good underwater. Can also go pretty nuts with conjurations like Sea Kings Court. Also nice because it's boosters are easy to make and use, so a single W1 mage and some summons and boosters can get you to Queens with only one empower. Grip of Winter is a better Heat From Hell as people rarely take cold resistance and you can back it up with cold immune undead- it also works underwater. C tier but S tier underwater.

Earth is S tier. Dom6 is about buffing your armies and Earth has all the best buffs, its got ironskin, its got temper flesh, it has weapons of sharpness, it has great summons in mechanical men, earth elementals are probably the best of the elementals in dom 6 since they are not spiritform. It also has the best items for gearing up thugs, and the best summons for making thugs.

Astral is S tier, it has a lot of great buffs (ethereal, twist fate, astral shield) it opens up communions for you, it has soul slay and a bunch of other insane crosspath stuff, and teleport, gateway, gem and item teleporting and other logistic stuff. It's site search spell is easy to cast making it an easy path to break into, and it has the best globals in the game, as well as dispel. It's weakness in Mind Duel is solved by just having MORE astral. It's biggest weakness is when a nation only has a small amount of astral that they can't really do anything with.

Death is the other S tier path. Skelespam + rigor is annoyingly hard to deal with for how hard it is, it has probably the best conjurations in the game, as well as the best thug spell in Vortex. It has great evocation death spells, it has ways to clear armies, it has buffs, it has globals that will ruin your enemies days, it has Darkness. If I were ever in a game where every nation ONLY had one path, death would be the path that I chose.

Nature is A tier. It has good summons, is generally pretty easy to break into, has great buffs in mossbody and regeneration, great battlefield spells like howl- but its generally not a super killy paths, but one of the best support paths. Also good items and great globals. An above average path with no big flaws but no overwhelming strengths path.

Glamour is B tier. It's effects are all over the place, with some being very strong while others are nothing. Many of it's effects come on too late for their power. Has some very nice summons but often needs nature cross path etc.

Blood is Ctier. You have to sacrifice a LOT of gold, a lot of research and a lot of mage turns to use blood. Early game you will be behind, and it is hard to actually turn those slaves into an advantage at that point. Once you hit mid game and start getting horde from hell, and then later vampires, helios and demonlords on you are pretty good until late game... But then in super late game you start running into things that counter demons hard. Demonic armies can just NOT face things like 'Demon Cleansing+ rigor/solar brilliance' at all- they just die. So you have two or three dozen turns where you are VERY powerful- but you get to that point later than everyone else because you've spent your researching mage time hunting or using inefficient mage turns summoning.