B&H is always a reliable and trustworthy dealer of the highest quality gear. Amazon has great shipping options, but you're never sure if you're getting good quality equipment.
Many of the brands that professionals trust, only sell through reputable resellers like B&H. Amazon may have great shipping options, but a lot of times your purchases are actually made through third-party companies like "Cheap Tech 4 U" and are simply fulfilled by Amazon.
I trust the quality of my craft to the gear that I have. I trust the quality of my gear to B&H.