Please allow me to share my opinion and if i did any incorrect statement, i am sorry. I am not an expert in SEO. Anyway, i believe that most of them are important. PR ( page rank ) : High pr sites usually can have all the update pages index faster compare with others because spiders never leave their site. SERP ( search engine results page ) : http://en.wikipedia.org/wiki/Search_engine_results_page. This is the key to get organic traffic from search engines. Organic traffic is the best because those visitors is your targeted audience.
PR does have it's importance....but in the end SERPs are more important. As far as linking goes, PR is important.....people only want to link with high PR sites, and if I had no PR I'd have a tougher time getting higher PR sites to link with me, and it's the links from these higher PR sites that do help the SERPS.....catch 22.
I am going to give both the same weight. PR converts to SERPs, IMO. Since high PR means you have more high quality links to your site. SERPs will follow since Google goes for site authority for SERPs my.02
PR -> Adds selling value to your site SERPS -> Brings natural visitors to your site (without any promotion)
I like this discussion, just wanted to add some questions? If SERPS (SEO optimization) is better, then why do people submit their site to Directories when all it will give is PR and a tiny amount of traffic? (Im talking about sites that doesnt sell links) Plus Link Exchange <-- does this mean that link exchange is only for PR rating and not THAT vital?
Link development is one part of SEO and submitting to director is an integral part of it, though how much benefit that brings is debatable. As for link exchange, well link exchange is not only done for PR but also for the traffic. For instance if you run a webmaster blog and exchange link with my webhosting blog, it would eventually bring us traffic from each others website, provided links are displayed prominently and the page is not a link farm.
Key words! If you have 1000 directories all saying "My Anchor Text" then you'll get better SERP for "My Anchor Text" when people search for it in search engines. PR can often be a side effect of many attempts at raising a site in the SERP... in fact, if you have a good site and work hard on promoting via SERP/SEO a higher PR will often follow without even taking it into consideration. The reverse can also be true, but personally I'd just assume start with high SERP and then let the PR follow, rather then the other way around.
http://thesaurus.reference.com/ is an excellent resource for such things if anyone needs help with it. Like if someone had a car repair site they could... and Car Repair Automotive repair Car parts replacement auto renovation car services we fix cars etc etc
This could be great if you are targeting a general niche. If you were to target a specific keyword "car" you would need to have car in your anchor... So it would be: buy cars, sell your car, blue car, i have a nice car ect.