I like Intamin. Their lack of fear to push the boundaries of what is considered sane and their butter-smoothness is just great. The track always looks beautiful, and how can you not love the launch. And Intamins look hot in the NL editor.
B&M is good too, but it always seems that they go too conservative. Over trimming rides and lack of ejector air is a turn off. However, their inverts and looping rides are great. Also, they just feel so graceful, especially their dive loops.
They are both great, but I have to go with Intamin in the end.