Biggest gripe I have with custom UIs is that a lot try to add something unique in places (I think) they shouldn't; around the actual boxes for chat.
Nothing would make me happier than something cleaner and more trimmed down than what Vert is. Just high quality clean boxes that stack and adjust along side each other nicely.
Vanilla EQ UI has those chunky bars along the top of each window, or those golden frilly bits around corners so if they get close to each other they clip through depending on which chat window is currently the focus.
Being able to remove the actual chat input on windows I never plan to ever chat in would also be fantastic. I only talk from one window. The rest is wasted space on each dialogue box.
Some phone pictures with what I mentioned circled:
I know some of that is there for identifying what is what, but I know what my party window is. I know what my dialogue boxes are displaying. The extra cluttery chunky bits just take away from precious screen real estate.