I was also torn between the two and got a Glo for Christmas on advice in the forum (and the fact that I was annoyed by Amazon's original 'No plans to launch paperwhite in the UK before Christmas' stance. Yeah they changed it later, but I was still annoyed & by then I'd had my mind made up).
I have also seen a paperwhite (family bought someone else one as a present) and prefer my Glo. I've also noticed the spots on the paperwhite, and it had a blueish glow with the light on. My Kobo Glo has more even light, no spots and is a more natural colour.
Some people moan the Glo's lowest light setting is too bright. I don't think it is. I came from a Kindle 3 with a lighted cover -- now that was bright, sometimes in your face light. I always read with my light on, so I can't comment on what its like without. For me it makes the screen stand out more and I've not noticed a massive battery drain.
I preferred the Glo's touchscreen. It's the type that doesn't require a finger to trigger the screen -- huge for me as I suffer with eczma and often read in bed while wearing gloves. Paperwhite needs a finger like a smartphone.
With a Glo, you get an SD card slot. As someone who tends to carry loads of books on her ereader (I almost filled a K3, which slowed a lot with lots of books and collections) this is a big deal. It also has really good integration with
Calibre for shelf management -- I have no idea what Calibre support the Paperwhite has (collections?). For me this was a huge issue, as I already had a big library managed through Calibre.
I also don't tend to buy books from one place, and have found .epub natively offered on more sites. While this isn't a huge deal with Calibre, it means I have to worry about conversion bugs less. Kindle books have to be in .mobi format.
Good luck with your choice. I've had my Glo since Christmas and not regretted it yet. My only negative with Kobo is the rather poor firmware support. It has a couple of bugs - check the threads on here. None of them are disastrous, they are just annoying. Amazon's Kindle customer service is also legendary, Kobo's can be frustrating. I made sure mine came from WHSmith - a nice big store who wouldn't quibble at a return in case of problems. Amazon's bookstore is better than Kobo's but if you read some threads on here, can use a search engine and Calibre you can use Amazon-bought books on your Kobo.