Argent Dawn appears to be in the worst shape, as Blizzard is sending players from that realm onto three different realms. Magtheridon seems to be the least busy -all they're transferring off there is the Horde-side players. They're also transferring players off of a few different realms to the newly-created one, Chamber of Aspects, so if you're looking for a new start, there you go to buy cheap wow gold.
We're just now coming out of our Thanksgiving turkey-induced haze here at WoW Insider, so if you've seen this already, forgive us, but Blizzard announced late last week that there's relief on the way for EU characters tied up by queues -they've got a whole mess of free migrations in the mix. We've got the whole list of transfers after the break as well.
These migrations are going until December 2nd, so now's your chance, EU players, if you're on the selected realms and have been waiting to jump ship.
Magtheridon (Horde only) => Zenedar, Haomarush
Neptulon => Ahn'Qiraj, Daggerspine
Outland => Bladefist, Karazhan
Ravencrest => Burning Blade, Deathwing
Sylvanas => Auchindoun, Lightning's Blade
Twilight's Hammer => Auchindoun, Lightning's Blade
Al'Akir => Dentarg, Xavius
Argent Dawn => Darkmoon Faire, Steamwheedle Cartel, The Sha'tar
Burning Legion => Ahn'Qiraj, Daggerspine
Crushridge => Bladefist, Karazhan
Drak'thul => Burning Blade, Deathwing
Grim Batol => Dentarg, Xavius