Hi Stodge, I thought I'd go through your requirements point by point. I've got both a Kindle 3 and an original Kobo so I'm familiar with both.
- reading books - Kobo feels a little better in your hands, but the Kindle has a better screen, better turn buttons, better navigation options, faster page turns, faster navigation of menus, faster resizing of text.
- reading newspapers - I have not used the Kobo for newspapers so can not comment on it. I can say however that newspapers on Kindle work well. Having page turn buttons AND a d-pad makes navigation through stories easy. Fast pages turns allows you to flip through the paper quickly. You can either pay to have papers or magazines delivered wireless by Amazon to your Kindle, or you can use a program like Calibre to create one for you for free (the success of this option depends entirely on how much content a newspaper puts online for free).
- reading PDFs - never do this so can't comment
- don't care about playing games or browsing or twitter access etc - me neither. The Kindle can do some of this but I don't bother. That's what computers are for IMO.
- I want to download books via wifi from a store - the new wireless Kobo and the Kindle can now both do that. I only have the original Kobo so I can't comment on how browsing and buying from the new Kobo works. I can say that buying from the Kindle store is really easy. Thanks to the speed of the device, browsing is fairly quick. The keyboard also allows you quickly search the store. The store on the Kindle uses "one-click" shopping that you'll be familiar with if you've bought anything from Amazon. So once you pick what you want and click purchase, you have it on your Kindle in about 30 seconds.
- I want to transfer PDFs from my Mac but otherwise I want minimal interaction between my laptop and the reader. I don't want to mess with converting files or removing DRM etc - if you're happy with the content available on the Kindle store, and fine with not being able to share that content with other company's readers, it's probably your best bet. Whether either store meets your needs obviously depends on what your reading needs are. If you like to read a lot of Canadian literature, you MIGHT find more on Kobo. Personally, I read a lot of non-fiction military history. Kobo has 760 titles. The Kindle store has 5,300. That said, they both tend to the carry popular new releases on almost any subject.