Bon... let's go !!
First of all, I use the French version of the game... so, mostly French addons, which may not be compatible with the Chinese interface (But, you'll find them in English for sure ... )
My "must have"
1) Titan Panel (A bar at the top or the bottom of your screen that displays what you want)
Add whatever you want to this one...
(Like TitanRuneCounter for Mage; ShardCounter for warlock; TitanQuest ... )
2) Fast Quest (Display the level of the mobs involved in the quest in your quest book)
3) Gatherer (Remind you of all the locations where you have ever found ore/herb/treasure/fish...)
3) Auctioneer/Enchantrix/Informant/EnhTooltip/Stubby (Search through the Auction House, and then display, under your items, their prices / Tells you the elements you'll have after disenchanting items / Prices of item from PNJ sellers)
6) Atlas ( Maps of Instances !!! and other maps as well...)
5) Mobhealth (Tell you the health of every mobs... calulate from the first hit... pretty accurate, and damn useful!! *Don't work in PvP, of course...*)
12) JudgeHype PNJ Tracker (Hum... a PNJ tracker ??!! )
0.7) Fishing Buddy (hehe... I'm already hearing her from here... But... well...)
两)Easy priest (One of these addons is really usefull, a right clic to selfcast a spell. Works with other Class too... like Paladin, Droïde...)
½) Arcanum (Special Mage
... A visual mod which help Mages to handle the water, the food, buffs and portals... )
Some of these addons requires dependencies... so be careful...
look for this when you download them.