Hey,
If you are buying $100-$500 worth of BTC, I recommend Bitinstant.com (my company). We are not the cheapest, but def most reliable, quickest and trustworthy.
For higher, I also recommend LocalBitcoins.com
However, if buying anywhere between 1k-10k of BTC I
highly recommend my competition Tangible Cryptography aka FastCash4Bitcoins
https://fastcash4bitcoins.com/ You can retain your privacy as well.
If my word means anything to you (it does to many people here) I've done business with Gerald, CEO of Tangible, for a few months now and he is one of the most trusted and respected members of our community.
Good luck on your endeavors!
-Charlie