I absolutely depend on Logic, it's fantastic library of software instruments with EXS24, and I've used it for so long, it's second nature to me. :)

I also love the side benefit of being able to express ideas on my iPad or iPhone using GarageBand, and the ability to open those ideas and refine them later in Logic is fantastic. There is no workflow, within my lifetime, that I can see replacing it, for myself, personally, anyways. ^_^