In my experience there are no straightforward answers to these questions but I will take a stab at answering and exploring them based on my experiences.

How valuable are link exchanges?  Less valuable than they used to be but they can still be valuable. When webmasters first discovered the power of the link they began trading links with everyone they could find. This was great for a while and sites began rocketing up the SERP. When Google began seeing real estate sites linking to viagra sites and all kinds of obviously manipulative linking practices they tweaked their algorithm to discount link exchanges. Now that does not mean that they are worthless though. I believe that Google's algo has gotten smarter and can differentiate an on topic and relevant link exchange and a link exchange meant to manipulate search results. If your site has a few high quality link exchanges as part of a diverse link profile you will get some benefit from link exchanges. If your site has nothing but traded links with any site under the sun you will not and you may be penalized as a link farm depending on how far you go.  One thing to note if you do a link exchange, make sure the site you are linking to is not considered bad by Google. Do a site: search in Google and make sure they are well indexed. Also look around the site and verify they are not doing anything shady. You can't be penalized by links coming to your site but if you link out to a bad neighborhood you may be.

How valuable are one way inbound links? One way links are the best links to get especially of they are natural. Generally they are better than link exchanges but again it depends on the source. If they are one way links from a well indexed page that is relevant to your site they are great. If they are links from a site that is not indexed or barely indexed they are not worth much. If they are from a site that has nor relevance to your site they may not be worth much. If they appear to be paid links they may not be worth much. One way links really can't hurt you but if the engine determines they are from a bad site or not natural they can be discounted or not counted at all. The goal should be to attract quality one way links naturally and if you can do that you will do well. If you try to manipulate the engines by getting spammy one way links you will not be penalized but the work you put into it will be wasted because those links will not help. In general one way links are the best but it is important to get quality links instead of a getting a ton of worthless links.

In your experience, what has yielded greater returns, strong partnerships or strong content?  In my experience it is content. The thing with great content is that it is able to attract great links and partnerships. So in essence by just getting link trades the only benefit I got was the link. By developing good content I am not only able to get good links but I have also developed real partnerships with related blogs and sites that are much more beneficial than a simple link swap. Content is king, not only because it sets you apart as an authority but also because it attracts good quality one way links and a more robust partner and customer base.

Sharon, a lot of times the positive benefits inbound links are difficult to see but as long as it is a good link there is going to be some benefit. It may not make you jump to the top of Google but it adds trust to our site and will eventually help you move up.

AR is huge IMO. It is full of fresh and unique content, which Google loves. It has tons of backlinks and lots of trust. Having AR links to your independent blogs and sites from AR can provide a huge boost. And as you build your AR profile up you build up the quality of backlinks to your other sites. It also opens your site up to a much larger audience who are interested in your services.