This is a tier list of all Genshin Impact characters (a.k.a. units) that can be obtained from banners, based on their perceived effectiveness, ease of use, and value in typical endgame content. 5-stars are assumed to be C0, while 4-stars are assumed to be C6.
Tier list
Dominant tier
These are the best units in the game. Most optimal teams will include at least one of them.
Bennett (off-field Pyro): a staple buffer and healer for most ATK-based carries.
Chevreuse (quickswap Pyro): the cornerstone support for Overload teams, Chevreuse also deals respectable quickswap damage when built for it.
Furina (off-field Hydro): An unconditional hydro applier who provides a teamwide DMG% buff, she is a top contender for nearly any team that deals talent damage and has a healer to counteract her HP-drain.
Kazuha (off-field Anemo): The best Anemo unit overall, he provides grouping and DMG% buffing, and he can perform certain double-swirl VV setups. His infused burst provides additional off-field elemental application.
Mualani (on-field Hydro): a Vape dps with the highest damage cieling in the game.
Nahida (Dendro): the best Dendro applier and EM-buffer. Her Hyperbloom team with Xingqiu, Kuki, and Yelan/Fischl is fairly easy to build and is very useful in this meta.
Neuvillette (on-field Hydro): does almost as much damage as Mualani while being more consistent and comfortable to play.
Sucrose (Anemo): comparable to Kazuha. Which is better will depend on the team.
Xilonen (off-field Geo): Like Kazuha, Xilonen shreds enemy resistances and buffs the team's DMG%. She has no grouping but provides healing to the on-field unit.
Excellent tier
These units are versatile and competitive in the current meta.
Alhaitham (on-field Dendro): competitive Quickbloom dps. His pull value is admittedly low if you have Yelan or C6 Fischl to be the 4th unit on a regular Hyperbloom team.
Arlecchino (on-field Pyro): high-damage but high-risk dps.
Charlotte (off-field Cryo): excellent healer to pair with Furina and make Freeze teams.
Clorinde (on-field Electro): excels in every Electro team archetype, especially if you can fit a shielder on her team.
Cyno (on-field Electro): excellent Quickbloom carry with Furina, Ororon, and Baizhu.
Emilie (Dendro): With her signature weapon and C6 Bennett, Emilie can deal excellent on-field damage. She also does great off field in a team with Pyro application.
Faruzan (off-field Anemo): C6 Faruzan is a crucial teammate for Xiao and Wanderer.
Fischl (off-field Electro): The best all-purpose Electro dps, Fischl is a staple for Aggravate teams.
Gaming (on-field Pyro): plunge-attack Vape/Melt dps with a high damage cieling that makes him the best 4-star on-field carry.
Kuki (off-field Electro): Her ability to trigger Hyperbloom from off-field while healing the on-field unit makes her important for many Hyperbloom and Quickbloom teams.
Lyney (on-field Pyro): a high-damage but high-effort archer.
Navia (on-field/quickswap Geo): best Geo dps, can frontload damage with her skill.
Ororon (off-field Electro): excellent in teams with Electro and Hydro or Natlan units.
Wanderer and Xiao (on-field Anemos): excellent with C6 Faruzan. Wanderer teams are good at crowd control, while Xiao's team with Xianyun is great in single-target.
Wriothesly (on-field Cryo): best Cryo dps, does well with Bennett+Xiangling+Furina.
Xiangling (off-field Pyro): still the only off-field Pyro dps for now, and quite strong.
Xianyun (off-field Anemo): required for most plunge teams, great healer for Furina.
Xingqiu (off-field Hydro): best off-field hydro applier, assuming you can drive his burst with normal attacks. He does less damage than Yelan but provides defensive utility.
Yelan (off-field Hydro): provides normal-attack-driven hydro application and damage along with a DMG% buff for the on-field unit.
Good tier
These units can be strong in certain teams or situations, but are not quite "top tier".
Baizhu (Dendro): As a healer, Baizhu has lost much of his relevance to Xilonen but is still desireable for Cyno mains. He can also be a good driver for Hyperbloom.
Beidou (off-field Electro): good against pairs of enemies, provides defensive utility.
Chasca (on-field Anemo): very good single-target Anemo dps who doesn't need Faruzan. Unfortunately, her performance plummets when facing multiple enemies.
Childe (on-field Hydro): His team with Xiangling, Bennett, and Kazuha is famously versatile in the hands of a skilled and invested player.
Hutao (on-field Pyro): single-target dps with a high damage and skill cieling.
Kaeya (off-field Cryo): good for Melt teams, especially Arlecchino Melt. Note that his c6 is unusually hard to get and his Cryo application suffers without it.
Kinich (on-field Dendro): single-target dps who synergizes with Emilie and Burning.
Kirara (off-field Dendro): best shielder for Aggravate and Nilou Bloom teams.
Klee (on-field Pyro): good dps with a playstyle some find clunky.
Kujou Sara (off-field Electro): specialized buffer for Clorinde or Raiden.
Nilou, Kokomi, Collei (Nilou Bloom units): Nilou's teams with Hydro and Dendro units are very good in most AoE situations. Her best teammates are Nahida, Kokomi, and Collei.
Ningguang (on-field Geo): does well with Xilonen+Furina+Bennett.
Noelle (on-field Geo): does very well with Furina in a Hydro/Geo team.
Raiden (Electro): A very good on-fielder with a lot of utility in her kit, Raiden is also the fastest off-field Hyperbloom trigger. However, Kuki is more practical in Hyperbloom.
Rosaria (off-field Cryo): good for Melt teams. At C2, she is theoretically better than pre-C6 Kaeya, with the caveat that her burst is stationary while Kaeya's is mobile.
Thoma (off-field Pyro): good shielder for Burgeon, Wanderer, Mualani, or Chevreuse teams.
Yae Miko (Electro): A favorite off-fielder for Spread and Overload teams, Yae Miko can also do well on field in Aggravate or Quickbloom teams.
Zhongli (off-field Geo): Though his shield is strong, Zhongli usually represents a trade of potential team damage for comfort. He is a great counter to enemy Geo shields.
Alternative tier
These 4-star and standard-banner units are decent alternatives to premium units.
Barbara (Hydro): a free substitute for Kokomi, and a decent teammate for Mualani.
Candace (off-field Hydro): works in Nilou Bloom, Arlecchino Vape, and Mualani Vape.
Diluc (on-field Pyro): best used with Xianyun+Furina as an alternative to C6 Gaming.
Diona (off-field Cryo): decent healer/shielder for Melt teams.
Sayu (on-field Anemo): decent 4th unit for the Bennett+Xiangling+Furina core.
Dehya (off-field Pyro): decent Pyro applier and defensive unit for Kinich or Clorinde.
Dori (on-field Electro): At C6, she is a decent Hyperbloom trigger and healer, particularly in a Quickbloom team with Furina, Nahida, and Fischl.
Kachina (off-field Geo): free Natlan unit who can use the Cinder City artifact set.
Keqing, Lisa, Sethos (on-field Electros): acceptable drivers for Aggravate or Electro-charged teams.
Jean (off-field Anemo): accessible healer to pair with Furina and use the VV set.
Layla (off-field Cryo): has the second strongest shield in the game.
Lynette (off-field Anemo): can provide VV shredding and a taunt for a variety of teams. She's also a good sub-dps for Faruzan teams.
Mona (off-field Hydro): provides a strong but brief DMG buff, good for Vape teams.
Tighnari (quickswap Dendro): A popular answer to certain annoying bosses, Tighnari is an accessible alternative to the best Dendro carries, Alhaitham and Kinich.
Xinyan (off-field Pyro): decent shielder and Pyro applier for Mualani Vape.
Yanfei (on-field Pyro): does reasonable AoE damage for a 4-star, and can generate a shield sometimes at C4.
Yao Yao (Dendro): an alternative to Baizhu, good healer for Aggravate or Nilou Bloom.
Yunjin (off-field Geo): A decent buffer and Crystallize "shielder" for Wanderer or Clorinde.
Obsolete tier
These units either compare unfavorably to similar ones or have kits that don't function well in typical endgame content.
Albedo, Chiori, Gorou, Itto (mono-Geo units): mainly used in off-meta triple- or full-Geo teams which cannot use C0 Xilonen as a support.
Amber (Pyro): useful in the overworld but not in typical Spiral Abyss content.
Ayaka (on-field Cryo): inconsistent due to her reliance on Freeze to keep enemies in her burst and activate her preferred artifact set, Blizzard Strayer.
Ayato (Hydro): obsolete in comparison to Kokomi and Neuvillette.
Chongyun (off-field Cryo): provides a Cryo infusion and cooldown reduction at C2+. Unfortunately, these benefits are not currently relevant.
Eula, Freminet, Mika (Cryo/physical units): could be relevant in situations where physical damage is desired. So far, no such situation has arisen.
Ganyu (on-field Cryo): outdated Cryo dps – Wriothesly is preferable.
Heizou (on-field Anemo): overshadowed by another 4-star, Sucrose.
Kaveh (on-field Dendro): appears to be a 4-star alternative to Nilou, but doesn't do a good job of it.
Qiqi (on-field Cryo): The worst 5-star unit in the game, Qiqi has no energy generation, and her teamwide healing is tied to her weak on-field attacks.
Razor (on-field Electro): His meme team with Nahida, c6 Bennett, and a hydro unit can be decent against groups of enemies immune to knockback, but there are better ways to use Nahida and Bennett.
Shenhe (off-field Cryo): mainly used in Ayaka teams – see Ayaka.
Sigewinne (off-field Hydro): There are other healers who do more for a team.
Venti (off-field Anemo): His style of grouping isn't applicable to most Abyss content nowadays. Kazuha is much better.
Yoimiya (on-field Pyro): There are a lot of better Pyro on-fielders to choose from.