I would have to vote for the MacBook. I have an iPad 4 and iOS just does not cut it for me. There are many good apps available and many people have gone to the iPad alone. That is fine if you are doing something that does not require any serious editing or designing. Most apps are watered down versions of their big brother apps that can run on a Macbook.
I need a laptop as the editing I do of photos and design work, can not be done on an iPad to my liking. I have tried and never got the same result as a laptop. I would go with the bottom end one as I have an iMac for my serious workhorse. I would use it for business, so therefore I would keep my large apps to a minimum. Only what I needed to conduct business at clients place. Which is what I currently use my MBP for.
But please do not get me wrong the iPad is a serious device and can do a lot more than it ever has. As I said a lot have people have gone for an iPad for everyday use over a laptop and I can fully understand why. Ultimately you will need to decide if it will meet all your needs. Especially if you have no other devices in case the iPad can not do it.
This is only my opinion. Thanks!