Imp Note: All starting SSR are support SSR in end game content unless you dont manage to get limited SSR dps you will be left with using these units I called supporters as dps.

Tier list :
1)Shiro :
Providing all elemental skill reset upon shield break using her at A3(3 star) so you can have your ALL weapon skill not just wasted on breaking shield but used again downed boss.
Provides high shield break and dps,ult charge with her skill, Extra dps with griveous 20% debuff(works on boss) for 7 second(Griveous triggers upon hitting ring once while other weapons ult is charged). High stat usefulness for each extra star up\ascension. Great for all elemental teams based on observation with multiple ingame teams using her for A3.
If you didnt pull Lin then she is a good stand in like in saki Ice team where you can use saki skill reset after using Shiros shield reset. Its always better to focus getting a dps to a6.
Heres a secret the clone(2nd you) from SSR relic also resets skill upon shield break i.e. you can use skills on boss total of 12 times(lol)
+she meow(literally) +she mail shells,fish +but most importantly she stretch that dump bacc

2)Tsubasa :
Provides high weapon ult charge on all attacks. The arrow rain on charged atk does good dps.
Each dash attacks stacks dmg buff upto 3 times for 21% dmg boost. Can freeze all enemies except bosses while using her with other weapons ult charged. High stat usefulness for each extra star. Easy to stack buff on her a6 tri dash atk. Gets replaced by frigg in Lin frost comp. If skipped lin then she is good standin for frost comp altho buff is hard to activate until a6. A6 Dash atk has high dmg if you connect all 3 shots.
-She is illegal +great fashion +cute-(door blows off)

3)Meryl\huma
Tanks are incredibly rare in tower of fantasy in both teams and in game characters. You are left saki fuwa next as your choice or the almighty immortal lyra insane tank whos healer class lol.
Meryl has CC immunity great ult to entrap the boss and +++importantly your team mates with the boss as you watch down on them as they crawl and scatter like baby spider out of your each ult and almost forgot high shield break.
Huma is the fire counterpart of meryl. She does everything as meryl
but +being extra defensive kit -you cant trap your team mates with her so I will advice going meryl.

4)Crow King,Samir,\All healers :
The reason why these guys are below is that the healers are good but nemesis is must needed for healing as only she can heal your party running marathon. Volt has only limited nemesis released so thats the only reason to use crow samir as dps while Fire,Ice,Phy got their dps already.
All healers are good you can browse them ingame but you will need best healer called nemesis for very hard content. The other 3 are used for supporting their elemental flagship unit(Nemesis volt,Frigg ice)
Crow king and samir got high atk speed+dps. But you can use these guys exclusively too they are good.