BrightTag, Qubit, SuperTag and Tealium all have great products, without a question, and they're are great for organizations with very specific tagging needs. With that said, Google has a history of building phenomenal products - Google AdWords, Google Analytics, etc. and their systems always work well together. With Google Tag Manager having a strong integration with their existing products and having no cost to start the choice was easy for our organization. Google Tag Manager has our needs covered and with it, we are able to deploy tags across multiple sites with ease. I would recommend it to anyone.