I don't think I'd want to simply rely on anyone, but use the rankings as an excellent head start in forming your own opinions and rankings. Each guy will place a different emphasis on age, experience, talent vs opportunity, how many years he looks forward, surrounding offense, etc. Each may have special insight or intuition with particular players. Homerism or other positive or negative biases (however unintentional) may come into play with some players.
I think the thing to do is to compare the rankings on a player by player basis rather than rely on any single guy's rankings. Note where there is general agreement and where opinions are all over the map. Use the rankings, and particularly the variances, to dig in and research on your own, forming your own opinion on a player, deciding for yourself where that player belongs in your own mind. If a staff member is an outlier with regard to a player, try to find out where he is coming from while doing your research, even if you still disagree with his conclusion. Maybe he's ahead of the curve on the player and you can learn why. Maybe he's behind the curve and isn't seeing what others are seeing. Or maybe he just sees things turning out differently than the others do.
See what staff rankings on the redraft side look like, particularly from those you know are putting in significant time developing their rankings because they are posting projections for the main site. Also, go beyond FBG for other opinions (that's blasphemy, I know, but do it anyway). I think it's possible for groupthink to seep into rankings -- though I do want to give these guys a lot of credit for being pretty good about not doing that -- so dig around and see what Fear & Loathing and others not connected to FBG think. See what others you respect on the message board think.
Then distill it all down and your own rankings will come. You may not even be able to explain why you prefer Player A to Player B, just that you do. And remember that your roster mix is important, that whether you'd want to own a 1st round rookie or a 28 year old vet will depend on more than a simple ranking of players no matter whose rankings they are. Your roster is a mosaic you want to put together piece by piece, and what pieces best fit at a single point in time will depend to some degree on the other pieces already in place.