Over a year ago, I tried playing on Oceanic US servers and the ping sucked. I even chose a Warlock specifically cuz if I went link dead, at least I had a chance of surviving if I was in the middle of a fight. But eventually, it got too frustrating and I quit. That's when I picked up on Chinese WoW and it was a wholly different experience. I could actually enjoy the game as it was intended... I think if you raid consistently, you'll be phenomenally frustrated with the game performance and therefore your personal performance.
On the other hand, some people I've heard have been able to play US servers, but none that raid high end encounters. I would probably opt for Taiwan servers if I were to jump off the mainland. However, I've also heard it may take hours for you to login due to the queues...
I remember when TBC launched in China, I'd often have to wait up to 30+ minutes to login... sucked.