Some SEO experts say that you shouldn't use the exact same anchor text on all backlinks that you create, because it wouldn't look natural to the Google algo. Instead, they recommend that you vary the anchor text.
Of course you should use at least one of your main keywords on most of the links. One idea is to make a list of different combinations of keywords plus other words that appear on the page.
If you have access to a tool that analyzes backlinks and you pick any random top 5 listings in the SERPS you'll see a very wide variety of backlinks. There usually only ends up being a handful of exact match anchor text rich backlinks and many other links including images, click here, the full URL, the company name, no-follows, etc...
In my opinion that indicates that a natural linking pattern is pretty diverse and varied. But the question is - is an unnatural linking pattern detectable and will it penalize or filter out your site?
If given a choice I would probably always go for the exact phrase the page is targetting.