All of them. However, if you want a priority order:
Lolivinci works damn fine at 10/6/9. Because she's a premium Arts looper though, I'd say this is easily the highest priority.
Kama is fucking broken and all of her skills are broken. Easy 10/10/10.
Dantès works damn fine at 10/10/6, but do you even want to use quick? His role is the same as Da Vinci's, so I'd say to choose one (Lolivinci) and work on the other later.
Mo-chan may be hot as fuck but she's not that good. Really wants to be 10/10/10 as well but, until Koyanskaya and Oberon, the others will perform better.
Anyone but Dantes, I guess, since all of them has NP charge, except Dantes, iirc. That said, only Kama has NP 2, so maybe Kama? But either way, I think it's just not Dantes for more efficient use of Lores.
@Guda-tan I think you can live without Kama's 1st skill maxed a bit longer. It's an absolutely amazing skill, but it's probably better to have one premium Arts looper online.
Thanks for the input. I ended up distributing the Lores, one each for Mordred, Kama, and Da Vinci for their NP gauge skills. The OCD in me won't have to endure seeing 28% or 48% or 17% NP charges anymore - that's a major pet peeve for me lol