iPad
If you already have an iMac or some other computer which isn't completely out of date I would go for an iPad. In spite of what others folks say you can do almost anything a macbook pro can do and it is more portable. The only reason I would get a laptop instead is if you need to access flash content alot on the go.
If you were to get a laptop to supplement your iMac I would certainly not recommend a macbook pro, I would more likely recommend the macbook air. Not sure how you are going to use it however so difficult to say. I take notes, surf the web, check e-mail, check social media, all within the iPad. So give it some thought.