I'm sticking with a MacBook. Multitasking is essential, and I believe it's missing on the iPad. I'm often syncing notes and pdfs with Dropbox, adding citations in Zotero and reading from an academic search engine at the same time. The best thing about my laptop is taking notes right next to my readings, with my assignments and Google open to handle quick questions. Perfect screen size and position, easy-to-use keyboard.
That said, I understand the urge for a stylus. I have a Livescribe pen and notebooks that I sync with my computer, so I have a complete database of my notes at all times.