Currently, my understanding is that there just aren't that many other LCs at the moment for Nihility characters that focus on DMG and CRIT. So at the moment, it's the best by a significant margin. The second-best is supposedly Good Night and Sleep Well (GNSW), which is a 4-star that's also exclusive to the gacha, but it's focused on increased damage based on DoTs. Now, it may be in the future that other Nihility LCs will come around that provide a reasonable alternative, but right now this LC is a rather significant boost.
That said... personally, I think Luocha is an extremely good healer in this game. His passive healing and HoT help
a lot with SP conservation, not to mention his passive heal also has a cleanse, so in a lot of cases it's just "set and forget." He's basically in almost all of my parties, regardless of elements, because he's just a self-sufficient healbot.
So... I guess it depends on what other sustain characters you have, plus how many jades you have. Statistically, your odds of getting the LC are higher, but if you have a healer gap her just having more damage isn't necessarily the most strategic. Like I said, it might be that other more accessible LCs come along later, or you could pull the LC during the rerun, possibly.
But then again, the normal rule of gacha applies: when in doubt, pull for your favorites. If you really like her, then something that will make you want to use her more will probably make you happier. And hey, if you kill things faster, less need for healing.