With those requirements I would go with Kobo, as I think any Android ereader is going to need more tinkering.
You don't want it heavy and you're going to carry it to work, so I don't think the Kobo Aura One would be the right one. The options I see are:
- Aura 2: It's the last model but I think it's a step back
- Glo HD: If you can find it in a shop it would be a very good option (better than Aura 2 in my opinion). It's a good option too if you can get it online (eBay or something like that)
- Aura (traditional): It's a very nice ereader and some months ago it has been sold at ebay by 50$, a wonderful price. If you find it with a good price, it is not a bad option either.