If considering a nuclear-powered aircraft carrier, steam turbines would be the preferred option. If the next generation of aircraft carriers is conventional, gas turbines would be the preferred option.
China can already build commercial nuclear power plants at 50% the cost compared to western counterparts.
The Hualong One nuclear reactor costs about $2.5 billion / gigawatt. This is an impossible price to reproduce in the West.
If Chinese engineers can figure out a way to do to naval reactors what they did to commercial reactors ---> cut the price down by 50% then the debate will be over. Nuclear power will be the default propulsion for large ships for the simple reason it will be cheaper.