If a full blown trade war happens between USA and China, who benefits more?

USA will benefit more in the short run. In the long run, everyone loses.

US imports way more than China, which is why Trump decided to go with the trade war to force China to stop their dumping practices. It's a protectionism policy which is not new. EU has done it before by introducing some anti-dumping laws, but whether it has been effectively prosecuting is another matter. Right now, US is prolly "winning".

But imports are there for a reason. No demand, no supply. Most of them are pretty essential stuff for food/buildings. I don't think anyone can produce as fast as cheap than China. The cost of living in US will increase by quite a fair bit. Retailers may also be put out of jobs because of the tariffs.

Singapore will also be impacted. Now China has to source its stuff from the neighbouring countries, competing with Malaysia, Singapore, etc for resources. We will prolly see our costs rise if China decides to jack up the prices to feed its demand...