Is there is no more PageRank, how do we check which sites are better than others?

Hypothetically speaking, if Google DID remove the Pagerank system, how would webmasters differentiate better ranked/optimized sites over less ranked/optimized sites?

For example, a PR10 site is obviously better than a PR2 website.

If PR didn't exist however, then how would we find out which site is better, or more valuable? Would people use Alexa? Or number of backlinks? Or how?

 

Then has Mozrank, Alexa, Hilltop, etc...

 

yepp, there will be plenty of less authorized service come out, might be a good thing

 

Look at the quality of the site and traffic.

 

Lift their tails.

 

it also can see from
traffic (Quality and quantity),
quality of site appearance,
quality of contents,
the position in search engine search result position based on specific keyword,

 

I use Alexa, it seems to work fine.

 

you can finds site quality with like Alexa, Number of back links, sites crawl page, search engine ranking if when page rank system is no more.