You will not be disappointed. As Nick points out, everything is centered around the Arduino Atmega328. The others have extra capabilities but can be "quarky". The Leonardo is a nice platform, but it is not an Uno. It is a little "clunky" switching CDC modes and can hang up. Serial communications through the USB are different and on some machines (PC side)so they don't work. Leonardo needs a little more development, but so did many of the Uno precursors.
First, Uno, then play 