High targeted traffic. If you can achieve it without good SERPs - great!

SERP's are more important to the sites catering narrow niche when your potential visitors base is limited and you want to get every one of them...

Google just killed value of the PR - no one will advertise on the sate based solely on the PR...

I agree with skinner: a lot of traffic is good, but if the visitors do not:
a) stay on your site (eg. because they got there by accident)
b) follow the funnel right through conversion into clients
you will never make any money.
I think it is finding the balance between the masses and the targeted traffic (ie. niches) that does the trick.