So I recently found the item I think is, if not the best item in the game, a very close contender. The "In Full Bloom Centerpiece" Its a statue that looks like a vase of roses. It gives off environment 4, which is enough to get you to +1 moodlet for decorations in a room. You can get it by getting a silver medal at a wedding, and it only costs $80 for each one, so pretty cheap.
Edit: skip these sections to find the actual workings of this item. I figured out exactly what it is.
In addition to this, it has a interaction that gives you a +1 happy moodlet for 4 hours, exactly like viewing a emotional painting. It also stacks with the moodlets from viewing emotional paintings, so its a unique, and quickly obtained moodlet.
Lastly, it has an emotional aura that gives +1 happy... but its intermitant. When I turned it on at first, my sim clearly had both +2 environment aura, and something else that was giving +1 happy (not from viewing) but now I'm having difficulties getting it. If anyone knows more, or figures it out, lemme know!
Edit: I played with it some more, and I have decided that this is, in fact the best item in the game.
It's the equivalent of a Good quality "Happy Painting".
It gives off an aura for the happy emotion exactly the same as a focused painting or other emotional painting would. In addition, you can view it in order to get a unique moodlet, just like an emotional painting, and that moodlet stacks with other emotional paintings interaction moodlet (like when you "View Focused Painting"). However, the happy aura does NOT stack with other emotional auras, so if you have a focused painting in the room, it will override the happy aura.
I looked into it a bit more, and you can stack the happy aura to a +2 with 3 of the vases. So, if you had a room with +3 happy from environment, and +2 Happy aura from 3 of these items, you could look at an emotional painting, look at a vase, remember a memory, and have any version of "Very Emotional" in the time it takes to do so (extremely quick), with a 4 hour duration. You could even lower the things you need to do by putting in a Let There Be Light! Laser Show, which gives a unique +1 happy moodlet to any sim that can see it. That would make a quick and easy universal mood room!
