
You’ll have the opportunity to grab a free copy of Luocha or Ruan Mei in Honkai: Star Rail as part of the version 3.2 update.
All Star Rail players will be able to claim a Golden Companion Spirit (a new type of currency) between the launch of version 3.2 and the end of version 3.4. These spirits can be traded in for five-star characters, but the only two options as of launch are Luocha and Ruan Mei.
That said, you may be wondering, “Should I pick Luocha or Ruan Mei?” The answer is: You should pick with your heart. If you love Luocha and want to collect his Eidolons, you can and should pick him. However, if you’re looking for an answer based on the meta, we get into it below.
A quick disclaimer: Your needs will vary based on what units you have, so make sure to also do your own research into what your specific characters may want! Our answers are not the be-all-end-all, since there’s no way for us to know your specific account situation.
Should you pick Luocha in Honkai: Star Rail?
Luocha is by no means a “bad unit,” but he’s just been very harshly powercrept by other sustain units that provide more than him. With most sustain now providing additional buffs, Luocha’s raw heals just aren’t enough anymore, comparatively.
That is to say that Luocha does play very nicely with units that consume their own HP, since he heals a lot. If you are building Mydei and/or Blade, then you may want to pick up Luocha.
Gallagher is a cheaper unit that also provides heals (and buffs), but since Luocha can heal automatically outside of his turn, it makes him a valuable pick for those HP-consuming DPS.
What about for Eidolons? If you’re considering picking up Luocha E1, then… well. It does provide a 20% attack buff when his healing field is active, but this kind of just brings up him to par with other existing sustain units. His Eidolons are not bad by any means, but just like the rest of Luocha, they’ve been powercrept by newer units, so they’re a little underwhelming.
Should you pick Ruan Mei in Honkai: Star Rail?
Ruan Mei was broken when she released and she’s still pretty close to the top of the food chain when it comes to buffers. She’s a pretty safe pick all around, as just about every DPS can make use of her buffs. She buffs damage, weakness break efficiency, and can extended the duration of an enemy’s weakness break, making her an asset to any team.
In a world where you need two unique teams to complete end-game content, Ruan Mei can likely slot into either of those teams, making her a must-have if you don’t have her already. The exception to this is if you’re drowning in other supports and buffers, in which you may not need her anymore. If you don’t have Ruan Mei yet and you don’t have the newer supports like Tribbie, Robin, Sunday, or Fugue, you should pick her.
What about for Eidolons? If you already have Ruan Mei and are pondering if you should grab her E1, then the good news is that her E1 is extremely strong, as it ignores 20% of the enemy’s defense when her ultimate field is up. Again, if you already have Tribbie or some other beefed-up supports, you may not need this buff.
Should you just hold on to the Golden Companion Spirit for a future unit?
This is a third option! If you have both Luocha or Ruan Mei already, or maybe you’re just not enticed by them, you can always hold on to the Golden Companion Spirit and spend it later on a different five-star character. You could even spend it on one of the original standard banner characters (Himeko, Clara, Bronya, Gepard, Yanqing, Bailu, or Welt), but we don’t really recommend doing so unless you really love those characters.

Hoyoverse has confirmed that more five-stars will be able to exchange for later, so while you may be waiting a good amount of time before that happens, this is a viable option.
Source:https://www.polygon.com/honkai-star-rail-guides/554895/should-you-claim-luocha-or-ruan-mei-for-free-in-honkai-star-rail