Very close to BTS Asok.
I booked a room without window. But my room doesn’t have the mouldy smell, thankfully.
If you have more budget, I would still recommend you to book a room with windows for fresher air.
My only complaint is the poor noise isolation. At 8am/9am, you can hear the noise of people walking and talking outside of the room, clearly. The cleaner also started to clean room. For 2-3 days, I was awaken by the walking and talking noises.