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)
http://www.curse-gaming.com/en/wow/addons-860-1-titan-panel.html
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)
http://www.curse-gaming.com/en/wow/addons-4691-1-fastquest-continue.html
3) Gatherer (Remind you of all the locations where you have ever found ore/herb/treasure/fish...)
http://www.curse-gaming.com/en/wow/addons-44-1-gatherer.html
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)
http://auctioneeraddon.com/dl/
6) Atlas ( Maps of Instances !!! and other maps as well...)
http://www.curse-gaming.com/en/wow/addons-539-1-atlas.html
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...*)
http://www.curse-gaming.com/en/wow/addons-131-1-telos-mobhealth.html
12) JudgeHype PNJ Tracker (Hum... a PNJ tracker ??!! )
http://worldofwarcraft.judgehype.com/index.php?page=aj-presentation
0.7) Fishing Buddy (hehe... I'm already hearing her from here... But... well...)
http://www.curse-gaming.com/en/wow/addons-2111-1-fishing-buddy.html
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...)
http://www.wowinterface.com/downloads/fileinfo.php?id=4852
½) Arcanum (Special Mage
... A visual mod which help Mages to handle the water, the food, buffs and portals... )
http://www.curse-gaming.com/en/wow/addons-4327-1-arcanum.html
Some of these addons requires dependencies... so be careful...
look for this when you download them.
Enjoy