What country had the first air force?

In terms of technology: United States > France, U.K., or Japan > Russia

In terms of Size: United States > Russia > People's Republic of China

(note, the above presumes you only count active-duty and ready-reserve aircraft)

Notes:

1) Israel, Japan, and South Korea largely purchase or receive aircraft technology from the United States, though the Japanese also have a significant domestic military aircraft industry.

2) The various NATO countries purchase much of their aircraft from the United States, as do several US allies, including the Republic of China (Taiwan) and Australia.

4) Most western European countries pool their combat aircraft design and manufacturing into multi-national consortiums. Thus, the United Kingdom, France, Germany, and Italy work together to design aircraft and produce them for their own air forces.

5) India largely purchases military aircraft and less sophisticated aircraft technology from Russia, though this is slowly changing (as they both purchase more from Western countries, and do more design and production themselves).

6) Technology is measured by stealth fighter and bomber capability.

7) Space technologies become increasingly important for modern day airforces, though they aren't always under an Air Force's control (many countries have separate military space commands).

Finally, remember that there are really a very limited number of countries which can produce modern military aircraft. Practically all of the world purchases their equipment from these countries; the US and Russia are the primary exporters of modern combat aircraft, with France next, and there are several European consortiums which produce a variety of military aircraft.