Mrs. Kujou Sara technically speaking, she is not really confined to any niche, and this is thanks to the fact that her buff applies similarly to how Bennett's does, granting a flat ATK bonus based on her based ATK to allies hit by her tengu marks, making her potentially very versatile.
Though her buff is a bit impractical to pull off and lasts for a very short time, but unlike every other buffer in this meta breakers, Sara herself actually contributes a lot of damage to her teams with her burst, especially with constellations.
So a typical Sara is a buffer that many teams could enjoy, but her high demand burst and very small buff window makes only a select few teams optimal for her, most of which include electro centered teams. Like how Shenhe has cornered the market of cryo centric teams, Sara is just naturally a good fit on electro teams where she can easily be batteried and apply her buffs to characters, like Beidou who can snapshot the buff, or Raiden who can front-load a significant amount of her damage inside the buff.
But to further this dominance within the niche of electro centric teams, Sara's C6 grants her the ability to buff her team's electro crit damage, which is actually precisely what makes her competitive as the game's best buffer for electro teams. Take for example this math regarding a C0 Raiden Shogun with an average build. A C6 Bennett with his very best gear surprisingly performs 2.6% worse as her buffer than a similarly invested C6 Kujou Sara, making C6 Sara become an unreplaceable role for Bennett or other buffers on electro-centric teams
Although Sara still falls short of other buffers in teams because she can't front-load all of their damage within her buff duration, Sara is still very potent in the teams that can, allowing her to dominate the area of electro team that contains characters like Keqing, Beidou, Raiden, etc.
With the introduction of Kujou Sara above, I believe that you realize how important to have a Sara in your electro team. In Genshin Impact almost all characters come from Gacha system which means you may spend a lot of extra money in your unlucky days for a strong character. In MMOWTS.com you do not have to worried about it anymore cause we have a large number of individual Genshin Impact Account for the players. In MMOWTS we have the amazing price compared other sellers and out delivery speed is also incredible. Every order could be finished less than 15min meanwhile if you have any questions, our online serves also be ready for all days and all times. Do not just watching anymore, click the link inside and get your Genshin Account to start a new adventure journey!