I think a combination of good SERP and good PR is the more desirable stuff. Which is most important to you will depend on the industry you are. One of my site Ozami Web Directory does not have very good SERP but since its PR went from 4 to 6 I have seen submission to the directory double but if I was to sell something that depends on lots of people finding me via search engine listing then SERP will be the most important thing to me.

thanks temi, nice comment, yes now I can see what is import depends on situation