Originally Posted by
Tagamogi
Kleave likes skins and loves onyx, so I find her favor quite easy to level using that and probably wouldn't bother with other stuff. If a person likes a specific item as opposed to a general item category, giving them that item will usually result in greatly increased favor, so her loving onyx instead of just "gems" means you are going to get a lot of favor for your onyx gift. Most players also find skins pretty easy to accumulate.
Flia - yeah, I don't talk to her much either now that I've finally gotten the last of my unarmed abilities. It looks like she likes willpower gels because they are in the general "potion" category, so while it seems like a decent way to level up favor with her, you will most likely not get quite as much favor as when gifting it to an NPC who specifically likes "willpower gel". Of course, I'm not sure if there is such a person...