Windows phones have a reputation for being app poor. How much truth is there to this? There are many apps I don't care about, but those I want, I want. Which has the best/most apps, Windows, Apple, or Android?
Yes, it is true and evermore so. Developers are abandoning Windows Phone because, well, it's dead.
As for which has the best/most apps between Android and iOS...Android has 2.8 million apps in the Play Store and Apple has 2.2 million on their AppStore.
The quality depends.
Apple normally gets the apps first because that's where the people most willing to pay for apps used to be. But Android has already surpassed Apple in terms of app revenue for developers so you're starting to see Android getting some apps first.