As you can see, I took regular lianna down the defense and health path. The costume version got a nice attack boost on top of the already high stat and only her health took a hit. I’m happy with my decision but you can compare and see what you would like to do. Most will tell you to concentrate on attack because that’s what she’s for. But I’m of the opinion that keeping her alive is more important.
Also I believe there is already a thread concerning this @Guvnor if you would like to merge.