Very tough to suggest something in this department IMO. In our home we have an Ipad Air (mine), an Ipad Air mini, a Samsung Galaxy 2, an older BlackBerry Tablet (wasn't bad actually), various older kindles and such, and lastly, a Microsoft Surface 2.
All have their pros and cons - Apple has probably the most/best apps, but the Andriod system is very good as well. The Retina screen on the Ipads is great, and so on. All that said, for productivity, nothing IMO beats the Microsoft product. It's all very familiar due to all of us being Windows bred, the keyboard is so so, but overall, if I had to only have one, this would be it.
With holidays coming, and the newer Ipads for sale, you can likely get a great deal on an Ipad Air, either size is great, very light, and both being a year old still have fantastic battery life.
Considering you've said you want to switch from a laptop though, I would say that looking seriously at the models which actually REPLACE a notebook, or do their best to, are your best options. The Surface is right up there for this IMO. See, typing is what is really going to screw with you IMO, going from a good notebook keyboard, to the silly glass screen type touch of most tablets. Either getting a BlueTooth keyboard, or a model with a good included keyboard, is a critical factor, again, IMO. The Surface comes with a reasonably decent one, and for 40$ I bought a solid metal Logitech KB that also becomes a sort of magnetized case for my Ipad Air. Don't forget this feature with whatever you go with, because the first long email or document you go to type on a glass mini keyboard will have you saying some very bad words, and longing for your laptop back - that's my experience anyhow.
We got our Surface 2 for 400$ on sale, which was 100+ less than an Ipad Air at the time up here in Canada, and then some. IMO the Surface blows the Ipad away for productivity stuff, while the Ipad is a bit better for lounging around type stuff, such as epub books, Netflix (looks great in 5200kbps Super HD with the Retina screen resolution), games, and the like. In your shoes it would be the Surface for me, with an upgrade to a "type cover" with moving keys, over the usual "touch cover" with the usual touch keys.