You always want to vary your anchors since Panda for your Tier 1. I had several sites that I was working on get sandboxed even though they all had original content. Once I starting picking the differences between the sites that still kept their ranks and sites that fell, and it became obvious to me. By fluke, because I was working on multiple related keywords per URL (because I wanted more traffic), I avoided being penalized because it looked more natural.
Think about it, how natural is it for a website to have 100% of inbound linking containing the same anchor text? Remember when Google penalized for keyword stuffing? Panda was the same, but for Anchor Text.
However, don't just use generic text + keyword as your anchors.
What I do:
Say I want to rank for the keyword "buy iphone 6".
I go to AdWords Keyword tool and put that KW in the lookup box. Then, I select the top 5 related keywords that Google gives me as suggestions. **Make sure you're sorting the suggestions by "Relevance" **
Then, when I do my link-building I use 30-40% of my money keyword, and the rest related keyword which I got through Adwords and generic terms like "Click Here" etc...
For my tier 2 links, I go back to AdWords and use the related keywords to produce even more keywords. I take about 50 related keywords from AdWords Keyword Tool, and use those as anchor-text for my Tier 2.
This has yield very good results across different link-building methods (i.e. high pr, original content, spun, cheap links, outsourced, and etc). Works for me like a charm.