I didnt play currently but maybe can give some clue for you.
From latency perspective , taiwan(xx to 300ms) realms giving the best respond, follow by US, then EU.
There is no SEA realms, nearest you could get is taiwan. But there is problem using taiwan realms, most of the player are using chinese to communicate, although we got eng guild as well, but definately having some hard time to comply with PUG raid and material/enchant buy/sell.