I had a ceramic tint (Huper Optik) on my E46 and I just installed a 3M tint on the wife's X5 this week. The price difference (almost 2x) wasn't worth it to justify the added expense of the ceramic.
The 3M tint I have is a little more on the neutral color/shading side vs. the Suntek tint that seems to be a little more green colored than grey colored.
As Brian425 said, the installer's quality and attention to detail in installation of the tint will be the main factor here. Most installers will know about the BMW's "dots" on the edges of the glass and also how to deal with them effectively.