The Lightweave weapon should be the only thing you're grinding. It's the most powerful in pso2 with no signs of new weapons coming after it.
The units are a hit and miss. Everyone wants the back with 120 base stats. The other two, arms and legs, hardly give enough to justify a grind for them.
Bruh, all 3 units are good. Cras arms off 220 Hp, the most HP out of any unit besides rappy shiny, which is a meme. Cras legs provide 30 PP, the most PP out of any unit.
Sure if that's what you're after. There are players that are focusing pure attack than anything else regardless of the health or PP bonus.
I mean, saying "I'm focusing pure attack" and "these units might suck" are 2 completely different things. Even ignoring that going "pure attack" is one of the biggest noob traps outside of like, time attack speedrunning, so many classes use Ph sub that not investing in PP would make you deal less damage. On top of that so many classes are PP hungry, and why would you not invest in Hp in UH content? The only class that shouldn't invest in HP is SU.