I miss the TBC days where people were set apart. Those who raided and were raiders had the awesome gear, worked hard for their gear, and had a real sense of achievement. Now you can do an easy heroic, have sub 30k dps in LFR, and do some dailies and become geared.
TBC was a pain in the ass for no reason imo.
It was like this. Spam trade chat for 3 hours to find people geared enough and good enough to do heroics. Then just when you were about to start you found out that a guy did not have the key even tough he thought he did. It was almost impossible to pug 5 good and geared players with the key for a dungeon. Even finding 5 guildies with the key was hard. Everyone had priority when it came to rep griding and there was almost always one who did not have the key for the dungeon you wanted to do.
Then you had this crazy long attunement for Kara. I don't mind long attunement for later raids but for the first raid of the xpac it was stupid imo. Specially since there was nothing else to do than Kara and rep grinding. We basically took 1 month helping people to get attune so we could build 3 raids and some backups to be ready for 25 men after Kara.
Grinding in BC was way too much over the top.
To me the best xpac stay wotlk. There was enough things to do to keep n00bs busy but the griding was for the most part not too hard and fun (save maybe for Argent Tournament). It was easy to farm food. Was easy to farm flask. Was easy to farm emblems yet fun. I liked the quest to kill a raid boss to get emblems. The normal raids were easy enough to pug but the last bosses were hard enough to give a challenge for small guilds. The heroic raids were hard enough to give a challenge to top guild. OS 3 drakes, Immortal/undying, A Tribute to Insanity/Immortality, Yog no keeper and LK heroics were really hard (with the proper gear). In fact pugs were still wiping on yog no keeper even at level 85. Blizz did a mistake by not removing the achievements and mounts when they released cata tough. wotlk was not perfect. Heroics dungeon were too easy. But for the most part it was a fine balance between easy content for n00bs and hard enough content and some crazy achievements/mounts for the top guilds.