1 - Is it Logic?
2 - If the answer to 1 is no, why not?
:P
More seriously, one feature that makes a major difference for me is the integrated sampler. Nothing else comes close to Logic and the EXS-24 sampler integration.
Then, let's suppose that every DAW offered a very similar package of features and was as stable, I'd say the way features are integrated, not just put together w/o a rhyme or a reason.
That's one thing that I dig about my current DAW - the consistency throughout the various menus, keyboard shortcuts and all components so that you can understand things instead of memorizing them or try to guess.
And, I know that some people hate it, but for me, having a DAW software that's designed to run on one OS, on one type of computer, by the same people who design that OS and that computer, has tremendous advantages.
More and more I'm trying to stick to what's in my DAW. I like the idea that, if tomorrow my computer dies on me, I can walk into a Mac store, buy a new Mac, download Logic from the App Store and be up an running w/in a blink, resuming the session exactly where I left it.
No need to worry whether or not my DAW software will give me problems w/ this or that component of my new computer or to re-install and authorize a bunch of things and update this and that.