This is completely hypothetical so please do not flame before you read the entire post. (Wasn't sure where to put this so I put it in general :P)
Anyhow... Okay, So, let's say that Blizzard has added a new feature to the game where you can reforge Item levels. When you choose to reforge an Item level it instantly boots the item level to the corresponding item level of whatever the highest possible quality in the game is. (So an epic trinket from BC would be like ilevel 359 and blue would be ilevel 345 but after patch 4.1 it would be a higher ilevel)
Also, sense the power of items goes by the item level when you boost the ilevel the stats would increase dramatically. (So they would actually be useful again)
Now, you can only reforge ONE item every THREE MONTHS. And once that item has been reforged it can not be reforged again for an entire year.
You CAN NOT reforge Legendaries OR tier set pieces. So please do not post legendaries.
So... What item would you choose to have again?
On my tank without a doubt it would be the Dawnforged Defender. The epic shield from getting exalted with the Shattered Sun Offensive. That is my favorite shield ever.
On my healer it would be the Vial of the Sunwell from Heroic Magister's Terrence.
Both are from BC for me but thats because there weren't many items in WotLK that stood out for me.