S Tier
Deadeye --------------------------------------------------
Super fast campaign, 
Snipe one shots most bosses. Feels really good right when you get into maps due to the ability to freeze targets. When you get into maps your defenses are bad until gear and freeze solves this issue. Along with high movement speed, the ability to one shot bosses this makes deadeye ice shot a very good starter.
Tactician --------------------------------------------------
Galvanic / Stormblast buff stacker - Ruetoo
Very good campaign. Just like deadeye it has great movement speed in the endgame along with crowd control from pin and full screen clear. It has the ability to one shot every T3 boss in the game. It only uses 2 buttons and never uses mana flask.
Spirit Walker / Deadeye / 
Amazon --------------------------------------------------
Twister - Snoobae | Twister - Kripparrian
Giga fast and giga damage in maps and campaign. CC with freeze to keep yourself safe. Insane target DPS in small arenas. Overall a fantastic build. There are a few downsides to the build though, its a attack to move build with 
Whirling Slash, it struggles in huge arenas like arbiter and it has a lot of buttons because it is a combo build. There is also a 
Whirlwind Lance version that is movement based that is very good but this version is Deadeye only.
Spirit Walker --------------------------------------------------
Companion Beast Master - CaptainLance9
"I am going to sit in my chair and the monkey is going to run around at 200 movement speed one shotting everything with big crits while I'm sipping on orange juice, ill put my reputation on it" - Captainlance9: Beasts have mods such as 300% crit chance, you can fish for them. Crit weakness and crit multi on jewels can give beasts big damage. Using parry to debuff the boss we are going to do some BIG damage. Even if the beast companion doesn't do a lot of damage, wolf pack might still be great.
Infernalist --------------------------------------------------
Has really great campaign due to how strong demon mommy damage and dash is. Recouped was buffed makes uncapped demon much better and it has enables Coc comet builds. It also has Low life crit multi builds with 
Nebuloch , Spell totems and a whole list of great builds.
Martial Artist --------------------------------------------------
All nodes OP. Honestly there is just too many builds to list and every node is just good. Whirling Assault is the go to skill and just destroy. There are a lot of interactions like 
Rain of Arrows to build combo and drop 
Tempest Bell everywhere. Strength stacking with Vorana keystone will get massive amounts of energy shield and get massive amounts of damage with facebreaker and Iron will/grip runes. There are just too many builds with this ascendency its just way too strong.
A Tier
Oracle --------------------------------------------------
Plants - DeadRabb1t | Plants - Raxx
Totems: 
Archmage totems might be a S tier build this league. Having no cost to your totems and getting all those defenses for free just sounds way too good. Multiple ways of building this with oracle, with either crit or poison paths.
Ancestral Bond has since been pre-nerfed, but the potential is still there.
Shaman --------------------------------------------------
Shaman Bear - Ronarray | Shaman Bear - CaptainLance9
The adaptive damage mods are pretty much max Diff because most fights are one element. Bonded runes give huge bonus all over and there are a lot of runes, AFTERALL ITS THE RUNES OF ALDUR LEAGUE. Bear feels decently tanky fairly early because of the built in armour. Good single target but half ass clear until you get herald of ice chains. Rampage is really fast and has great clear and single DPS but looting is pain.
Lich --------------------------------------------------
ED Lich - DeadRabb1t | ED Lich - Ronarray
Both plants and Essence Drain are both viable and extremely comfortable league starters. Potentially there could be tons of broken interactions with the bypass mechanics. The only reason this isn't a S tier league starter is because it doesn't have massive single target burst and not enough movement speed but it has great defense and mana QOL to close the gap. Low life tech = good.
Disciple of Varashta --------------------------------------------------
Infernal Legion Beasts, Spectres. With 
Kelari's Deception the ascendancy is just very strong right away. Minions have pretty bad clear compared to most builds but can be really tanky and do big single target damage. This ascendancy is just good overall for a lot of different casters also, its very tanky HC ascendancy, its just STRONG. Melee splash might change the way minion clear feels so it might be MINION LEAGUE.
B Tier
Witchhunter --------------------------------------------------
Grenades - Big Ducks | Permafrost - Pohx | Stormblast - Woolie
Witchhunter still has huge defenses in the game but really lack the offensive firepower to be a high tier softcore ascendancy. Grenades remain strong and the new base type might provide new toys. Permafrost rounds is just comfortable all the way through the campaign into end game. Both of these builds on Witch aren't flashy isn't insane but gets the job done all the same.
Invoker --------------------------------------------------
Honestly Invoker is only good for HC because martial artist exists. It gets outclassed by that class in almost everything but is still a solid ascendancy overall.
Acolyte of Chayula --------------------------------------------------
New alternate ascendancy is coming with this and its going to be REAL good. Copium. Great for sekema carries.
Stormweaver --------------------------------------------------
Spark Leaguestarter - animeprincess
Still the go to for elemental skills that are normally unplayable by other ascendancies. There are niche builds that can only be played on Stormweaver but still not as strong as the other casters. If Overabundance III exists this will open up some builds.
C Tier
Gemling Legionnaire --------------------------------------------------
Which ever skill has a good alt quality. We don't know anything about it can be really good or complete trash. We do know one thing, motes are a complete joke and we have no idea why this was even made.
Chronomancer --------------------------------------------------
Time Freeze is fun. honestly still gets out classed by the other good casters.
D Tier
Smith of Kitava --------------------------------------------------
Reason 1 for D tier = warrior Reason 2 for D tier = maces. There are some cool fire spells builds but over all the builds are slow, dont do tons of damage and just gets outclassed by so many different classes.
Ritualist --------------------------------------------------
Not the best for things but this league offers some new toys like the thorn ring. Now you can put your thorns damage on every attack, could lead to some cool builds. Other rings got changed too, so who knows. Mostly its still a ring based ascendancy and is not that strong for league start.
Warbringer --------------------------------------------------
The new bow will work well with warbringer but playing a bow build just for the block has a huge opportunity cost that probably wont pay off.