Honestly, I trust reviews from non-rap sites these days more than I do from rap sites, aside from a few. Rap sites may be more well-versed in the culture, but it's not like they always use that knowledge/understanding in their reviews. Most rap sites/mags are going to give artists higher ratings so they can maintain relationships with them to get access for future stories, or to get them and their labels to buy ads. Or, they'll play the middle ground: an album can be 2-star quality, but they don't want to completely kill the relationship, so they give it 3.5 stars. Plus, sites are going to play up to what their readership is: if you have a site known for underground hip-hop, for example, they're likely going to trash mainstream rap based on who is reading the site, even if the album is good.
At least with Anthony Fantano or Pitchfork, they seem to be giving their real opinions, they back up those opinions with strong explanations, and they take definitive stances. And if they're not an exclusively hip-hop site, they have less reason to pander to hip-hop artists and their labels with BS reviews.