It has been a long time since the last world war, around 70 years in fact. Since then a lot of things have changed. Countries that were weak back then are strong now and vice versa. The weapons from back then are ridiculously outdated. Our technology is so much stronger now than it used to be. The press of a button could literally spell the end of the world.
There is no way to know for sure which country would win so we must to take into account a number of factors. The factors on which country could win WWIII include: How much military personnel each country has; Total naval strength; the number or aircraft each country has; number of tanks; the percentage of money each country spends on military; the estimated nuke count (no one knows for sure) and intangibles.
Lets hope we never find out if we are right.
Turkey has the second largest standing armed force in NATO
The ever present threat of North Korea keeps South Korea ready
France manufactures its own military equipment
British military have experience, strategic location and nuclear arsenal
China outnumbers all other nations in manpower
Russia boasts nuclear power and influence over oil producing regions
US military dominates in firepower, tech, and the world’s largest defense budget