Search engine traffic may be a little better by itself but both work excellent when you do them together.
Link traffic can be very good especially if it's in the same niche and targetted, it also helps with your search engine traffic, if you are getting backlinks from similar sites in your niche
Referral traffic from other sites are also significant on their own way.. while on other hand the search engine traffic are also important because it came from exact search term searched by people from search engine and then they are landed on your webpage and your webpage got visit of that user.. that is the way to get quality revenue...
do you mean a similiar theme like similiar topic?if that is what you meant to say than it will as targeted as search traffic because it's like people are searching for a certain topic and they find your link and go to your site.very similiar to what happens in search traffic
i prefer SE traffic but some websites and blogs need to get traffic (UNSTOPPABLE TRAFFIC FROM FACEBOOK) the more traffic the more money you can make, useful thread at http://forums.digitalpoint.com/showthread.php?t=2515553
It depend while you need believe that some people might earn money from traffic that only from ads or social media and zero from search engine. If you earn money from organic search , you might need to focus on SEO to rank better in SERP and get more traffic . From the site ads , usually the traffic need to be quality enough only have high conversion rate. That you you need to testing and use Google Analytics to check the conversion rate that is it worth to pay for the ads placement.
In most cases, the SE traffic would be much larger than the traffic from any specific websites. But in some cases, maybe not. For example, if it is very difficult for your websites to rank high at search results, but you have some resources at hand which can easily bring you targeted visitors, to build a link on it, such link is much better than thousands back links you build only for improving the rankings at search results. On the other hand, the links which are supposed to attract traffic, not merely get your website rank high, would in the end, helpful to the ranking-improvement. So, if in your case, you think the link traffic is more effective compared to SE traffic, try your best to find more related sites to build the same-like link.