The title comes from a top-voted question from a Simple Questions post a couple days ago.
I wanted to start a discussion on the topic because I think it's a common sentiment. Here's another example:
I'm in the decision-making process for a new card, and this sub is way more generous to AMD than almost every other community I use as a resource.
However, the idea that people making recommendations on buildapc unduly favor AMD is a misconception. The fact is that every major source that is up to date is also recommending AMD at this time.
See AnandTech's Best Video Cards: June 2014
and Tom's Hardware's Best Graphics Cards For The Money: June 2014
AnandTech's recommendations are:
AMD R7 260X for <$100
AMD R7 265 for $149
AMD R9 270X for $179
AMD R9 280X for $279
AMD R9 290 for $389
NVIDIA GTX 780 for $499
NVIDIA GTX 780 Ti for $649.
2x AMD R9 290 for $800
You can see that AMD dominates the recommendations, and there are only two price brackets in which NVIDIA is recommended. Essentially, if you want to spend less than $499 or more than $649, you should be getting AMD.
The story is similar with Tom's Hardware, which recommends:
AMD R7 240 for $70
AMD R7 250X for $100
AMD R7 260X for $120
NVIDIA GTX 750 Ti (Honorable Mention)
AMD R7 265 for $150
AMD R9 270X for $190
AMD R9 280X for $280
AMD R9 290 for $400
AMD R9 290X (Honorable Mention)
NVIDIA 780 Ti (Honorable Mention)
AMD R9 295X2 for $1500
The list from Tom's Hardware is more concerned with value for money, if the title is to be believed, and NVIDIA drops out of the running altogether, except for two honorable mentions.
Conclusion: The fact that people on buildapc are overwhelmingly recommending AMD right now reflects the recent price changes that have made AMD the better buy in just about every price bracket from $100 to $1500. There is no undue AMD bias, and I surmise that if NVIDIA were to drop its prices accordingly, recommendations would quickly swing the other direction.