On doubtedly the one way link is the best options. The one way links will increase more traffics for your site and helps for improving your search engine ranking. Two way links or reciprocal links are effective for related quality sites. So most of the times webmasters prefer oneway links to increase traffics.
All your search engine optimization activities are directed to achieve one single goal - traffic. If your links (both one way and reciprocal) suffice this basic requirement, then go for it.
Two way links for traffic. One way links for SEO. Another gr8 option is A link to B, B link to C and C link to A!!
One way links are very useful and imp to a site to gain ranking and boost the keyword position in SERP.