I chose the Blendtec over the Vitamix for the more compact design, easy clean surface and because the blades are designed to not be sharp. Overall I'm very happy with the abort to make a bury smooth milkshake or smoothie and I've made some delicious soups, guacamole and hummus as well.
Only criticism is that Blendtec doesn't come with a tamper and says it is unnecessary and messy. You have to add extra liquid without it and the solution of the smaller twistjar is way more messy.
I purchased an aftermarket lid by Alterna that comes with a tamper and couldn't be happier.
I debated about buying a "good" blender. I went with a Vitamix. I was not happy with it. I thought, "if I am spending this kind of $ on a blender, I want one I like". I returned the Vitamix (I bought it at Costco) and got a Blendtec. I love it.
Even though it has a big sound, it works well and my wife used making lots of food. As we just bought it, we don't know how durable it will be but I believe it will be also used for many years.