I didn't really recommend them because I don't have personal experience with any of them although I have second-hand info about one of them (relatives were lodged there several days years ago and didn't have complains). I just quoted 2 accommodations that I've seen from the outdoors on my visits to Madrid and that are really close to Chamartín train station (in fact, one of them is in the train station itself) being the closeness to Chamartín train station the main reason why I quoted them (that's why I said if you just want an accommodation close to the train station). Both of them have a star rating that implies that they should be fine for the purposes of the OP in that thread if they were within his/her budget although, of course, each one's personal expectatives about an accommodation can make a difference. That's why to read reviews about an accommodation is always a good idea and why I suggested the OP of that thread to read reviews about whatever accommodation s/he planned to book regardless the area of Madrid where it was located. Being the two hotels that I quoted part of hotel chains, it's easy to find reviews online about them to get a better idea of what to expect and book accordingly.