The Patriot and S-400 missile systems are used to defend the sky from enemies. The S-400 can destroy Tomahawk cruise missiles and can also detect stealth aircraft. It can detect other targets at all altitudes of their combat and employment and at maximum ranges. This air defense missile system can simultaneously engage 36 targets. The Patriot missile system uses high-performance radar systems. The missile has a range of 43 miles (70 km) and a speed in excess of Mach 2. It has a maximum altitude greater than 14 miles (24 km). Which is the better option for defending the sky?
Patriot (MIM-104) is a long-range, all-altitude, all-weather air defence system to counter tactical ballistic missiles, cruise missiles and advanced aircraft. It is produced by Raytheon in Massachusetts and Lockheed Martin Missiles and Fire Control in Florida.
Patriot is in service with the US and allied countries including Germany, Greece, Israel, Japan, Kuwait, the Netherlands, Saudi Arabia, South Korea, Poland, Sweden, Qatar, the United Arab Emirates, Romania, Spain, and Taiwan.

US forces deployed the Patriot missile systems during the 2003 Iraq conflict. The systems were stationed in Kuwait and destroyed a number of hostile surface-to-surface missiles using the new Patriot advanced capability-3 (PAC-3) and guidance enhanced missiles.
The US Department of Defense (DoD) approved the deployment of additional forces and a range of military systems including two Patriot missile batteries and a Terminal High Altitude Area Defence (THAAD) to Saudi Arabia in October 2019. The deployment was in response to a drone attack on oil facilities operated by state-owned oil company Saudi Aramco in Saudi Arabia in September 2019.
The S-400 is a mobile long-range surface-to-air missile (LR-SAM) system developed by Almaz-Antey, a Russian state-owned enterprise. It possesses the capability to take down multiple aerial targets including stealth fighter jets, bombers, cruise and ballistic missiles, and even unmanned aerial vehicles (UAVs). It possesses four different kinds of missiles that can engage beyond visual range (BVR) targets up to a range of 400 kilometres and it also carries two separate radar systems, which can detect aerial targets to a range of 600 kilometres and can simultaneously engage 80 aerial targets.

S400 vs Patriot: Best Air Defense Choice?