I have the Onyx Boox i62HD and I'm very happy with it. 6'' screen, no ads or forced content, I add the books via the USB port, and the firmware provided by the online store "ereader store" has several languages, including Swedish. It does not come with a Swedish dictionary, but you can add the dictionaries you want. I sent to it the books I have in calibre, too.
The only thing I'm not sure about is the batery: I've had my e-reader for 2 weeks, during this time I've used it a lot (several hours every day) and the batery is almost full, but I've had it connected to add new books, scientific papers... So I don't know how much it would last without connecting it.