Which one more important? Google PR or Alexa Rank? Some people tell me that Google PR more important for our site than Alexa Rank. But others tell me that Alexa Rank more important than Google PR. ???

Google Ofcourse. 80% of the traffic comes from google

Yeah... So, do you think it's more difficult to achieve high Google PR than Alexa Rank...?

I think achieving PR is harder. Alexa does get some of its rank off search engines anyway I think and getting link backs is hard.

Honestly? I've never really used Alexa, only heard it mentioned in varying places. And since roughly 90% of the human population uses Google, I'd vote for Google PR because I'm more used to that one.