Vocabulary question

How do you express the sentiment of "I'm speechless" in Chinese? The problem is I'm finding too many options. Can someone comment on which of these is actually used, and what the differences are?

1) 语塞

2) 哑口

3)张口结舌

4)无言可对

5)有嘴没舌

6)盘倒

7)张口结舌

8) the most mysterious of all, 汗, about which mdbg says "perspiration / sweat / CL: 滴, 頭｜头, 身 / to be speechless (out of helplessness, embarrassment etc) (Internet slang used as an interjection)". I have no idea how to translate that into actual usage.