I think skill effects are the best value, and of those, the ones that most drastically change the skill’s appearance. I typical create new builds based on the skills I want to use and how they can look and function, so something like the cherry blossoms effect for Smoke Bomb encouraged me to create a ‘samurai’ build. Although, this was also because I wanted to make a ‘samurai’ build before I saw the skill effect (due to basically wanting to recreate classes from another game I play). Thus, a large variety of skill effects would be good.
Honestly, there’s a lot. I want more ‘fantasy’ stuff (elves, dragons, fairy type things). I want some more ‘tech’-based stuff (turrets, explosive effects, lasers). More animals/forms for the primalist (snake forms, bull/minotaur, elephant, and so on).
I’d also love to see more pretty/elegant stuff like dresses for my acolytes and rogues (female versions of the other classes when?).
And voice-over packs would be really cool too, though I guess those might be wishful thinking.
Pets, evade effects, portals, and weapons/armor.
Pets because they sort of feel superfluous, like, if I want something following me around I’m probably playing a minion build, right? So they’re pretty much only for builds where I’m playing a character that doesn’t have a combat minion for gameplay reasons, but thematically has one, like a ranger with a scouting owl or something. Pets should basically be able to replace minion skins if you want them to, so like that one owl pet could be just a pet, or you could use it as the Falcon instead. Also, we should have like a pet-battling mode (you know you want it too).
Evade effects I haven’t bought because I never use evade. Like, I use things that change evade into other things (Crab Ring, Swiftness gloves) more than I use evade. And it just never feels good to use otherwise. Really, it would be better if evade mtx were also movement skill effects, or came with equivalent versions, because some of the evade mtx do look pretty nice.
Portals I just don’t feel like I use them enough to want different visuals for them.
Weapons/gear I haven’t bought any because I’m changing my gear often, and gear mtx feels like a ‘finishing touches’ on a build/character. They’re also just not generalized enough, I think. Weapons need to be more of a set/theme or not be tied to item type beyond 1h vs 2h; for example, I don’t use maces on any builds due to thematics, but if I could use say, a sword skin, on a mace, then I might be more inclined to buy it (and vice versa).
Sorry, my reply was kind of rambly, but there’s so much that could be added or improved it’s hard to address it all.