So if you've been playing Genshin lately then you're probably aware of the fact that Klee is back and you may also be aware that we also recently received a new 4-star pyro catalyst user with a focus on charged attacks named yanfei. Now if the way I described yanfei sounds familiar then you're probably aware of just how similar she is to Klee. Mihoyo has been pretty good so far about keeping the characters diverse with only other examples of characters with similar purposes being sucrose/venti and roasaria/eula and both of those cases have two characters who are different enough to make one or the other more useful depending on the team. Yanfei and Klee do technically follow this pattern, they both have different mechanics and uses and one may be preferred over the other depending on preferred play style but they do basically function the same in the same teams. Having said all that, today I plan on looking at both of them and comparing them to one another to determine which one is better and to determine just how different they are. The judging will be based off the following six categories:
DPS potential
Utility
Survivability
Constellations (and how necessary they are)
Exploration
Ease of use

DPS potential: this is going to be a straight numbers game. We can talk all day about how certain circumstances make one character better but that's going to be covered in ease of use so this is just talking about the amount of damage these characters can do. Upon first glance, yanfei seems like an obvious winner, all of her talents have higher damage multipliers. Her elemental skill has a much higher damage multiplier, hits multiple enemies, and allows her to fire off one of her super powerful charged attacks immediately afterwards. Her elemental burst's damage is just kind of okay but that's not the main draw of the burst so it doesn't really matter. Klee on the other hand has much smaller multipliers but much bigger range, all of her attacks have splash damage and they're all classified as heavy attacks which means they can break shields and rocks much faster then anything yanfei can do. Klee's talent also drops mines which can be pretty easily combined with an anemo user to increase her damage even further. Her burst also mitigates her multiplier problem by essentially just increasing her multiplier by like 50% and pushing her multipliers ahead of yanfei. Yanfei also has to worry about breaking through rock shields and worrying about her stamina, Klee doesn't have this problem since her passive talent allows her to use her charged attack for free after a couple of normal attacks. Overall Klee is generally going to have better damage outside of boss fights where yanfei is probably going to pull ahead just slightly.

Utility: Klee has none and yanfei only gains some at C4 and it's in the form of a rather pathetic shield tacked onto her elemental burst.

Survivability: this is a little more interesting that the utility section because it brings us back to the stamina problem. We've already discussed that yanfei does have to worry about stamina management and that at C4 she gains a little bit of shielding. Klee having "better" survivability will largely depend on the players ability to dodge effectively. In all fairness, survivability isn't something these two need to bring to the table as most players will probably have someone more Tanky to switch to when they need to dodge.

Constellations: Klee in general does very well even at C0 however just about all of her constellations are useful with the only notable exceptions being her talent leveling ones (which is par for the course). Overall Klee can be kept at C0 which is an incredibly good thing since she's a limited 5 star. Yanfei really wants C6 to function her best. Her C1 and C2 are incredibly important to making her a more consistent and reliable damage dealer and her C6 pretty much fixes all of her stamina problems while also increasing her fire power. Yanfei is a non-limited 5 star so it's not impossible to C6 her how we it still does require a lot of additional investment that Klee just doesn't.

Exploration: neither of them have like super amazing exploration abilities. They can both place pins on the map where they're specific region's unique materials are located. Klee's is the more useful variant because the mushrooms that she, Barbara, and Mona need to ascend are a lot easier to find with her and there really isn't a equivalent in liyue. In both cases, their abilities are geared more towards newer players as more experienced players will probably have already marked up their maps with the locations of all these materials.

Ease of use: this is a harder category then the others because it largely depends on your preference when it comes to gameplay. Klee has long animations and one of the hardest animation cancels in the game while yanfei requires a good sense of rhythm. Yanfai requires very rhythmic timing to maximize the potential of her brilliance buff as well as to cut down on the amount of time between attacks. This gets a little harder at C4 since the usual pattern of tap-tap-tap-hold becomes tap-tap-tap-tap-hold and her attack pattern is clearly designed for the former so it can get a little harder to control. Klee's animation cancel is hard to master but if you don't get it down then it becomes harder to I-frame attacks and she doesn't switch into charged attacks very easily.

Conclusion: at the end of the day Klee is still the better unit. She has better damage for abyss and for most other encounters and she works better with the same supports that yanfei does (venti/sucrose and xingqiu). Klee is a bit harder to use but once you get the hang of her then she becomes a bit of a monster. Yanfei is still very good and I'd even go as far as to say that they're both worth raising if you have both and need the extra main damage picks for abyss or certain domain challenges. If you're building a team with them then I would recommend pairing them with a shielder, sucrose/venti, and either Bennett or xingqiu. Fischl, Rosaria, qiqi, and Diona can also work if you want to go for a different elemental reaction and beidou can also work as a shielder replacement as always.