Most OS X users will expect your App to be packaged as a Disk Image (dmg) file. It also happens to be Apple's preferred method of distributing files. You can use the "Disk Utility" under /Applications/Utilities to make a dmg.
Installer Packages (.pkg files made with the "Package Maker" utility) are fine, but they should only be used when you can't fit everything inside of the Application itself.
Installer Packages (.pkg files made with the "Package Maker" utility) are fine, but they should only be used when you can't fit everything inside of the Application itself.