Your question is interesting. You should have stumped many people. I don&;t know what is the best, but I think if you want to stay in Changbai Mountain and you can soak in hot springs, I recommend it to you: Crowne Plaza Changbai Mountain Hot Springs Resort.
This is a hotel with high specifications and complete facilities. It is located in Changbai Mountain Scenic Area, near the transfer center. It is convenient to see Tianchi or Waterfall, and the price will be high if the specifications are high. If there is no price limit, this hotel is quite comfortable to live in. The hotel has a bar, gym, coffee shop, business center, free parking lot, restaurant and so on.
Stay in this hotel and go to the main peak to see Tianchi. You can take the VIP passage. After going down the mountain, there is a car to take back to the hotel, which is a real VIP-level enjoyment.