Well if your budget allows for over 1600rmb per night (200USD++)
Then best to go for the Sofitel legend as I have heard of many good reviews. Plus if your gold or platinum you would want to work out the best way to upgrade to the perfect room/suite.
Smallest rooms start at around 70m2. Ringing up or emailing the hotel about if they allow upgrades between the room you want to book and what you might get to avoid the "We don't do upgrades between these levels".

It does seem they don't have a lounge but have drinks downstairs for get together with other guests for socialising.

Rooms would still be quite new as its less than 2 years old.

The regular Sofitel is about half the price of the legend usually. Has a lounge. But is a good 5+ years or older and hence things have more wear and tear. Majority of reviews are good but some issues with some people too.

Grand Mercure and Mercure I dont know about. Mercure would be taking a risk it might be rough check trip advisor. Grand Mercure should be okay somewhere between those 2.