5: Mini-DIN connector - a useful connector mainly because you can use the numerous pin configurations for multi-signal connections. The miniature size is handy as it takes up a lot less space than other multi contact connectors. They do limit the signal and are not generally used for high quality audio signal processing. Nonetheless, a very useful connector.
4: XLR connector - the first choice for live pro-audio kit. Many PA systems use the standard connector with many lighting systems adopting this as their connector of choice. Most commonly seen as the 3-pin version, this will go up to 9-pin for high end aircraft applications.
RCA connector - sometimes called a phono connector, it's great because if you need to separate the L & R channels these connectors are the ones for you. They are the standard as far as this goes. Simple and effective, designed in the 1930s, still around today. Say no more.2:
TOSLINK - as I'm a big fan of fibre optics this comes close to being my personal favourite. Optical cables are not susceptible to electrical problems such as ground loops and RF interference. For digital music this is the best cable you can use. Although I have to admit I am very proud of my vast vinyl record collection!
1: The TRS (Tip Ring Sleeve) connector - that's the 3.5mm mini Jack to you and me! My personal favourite. Why? Because it just works so well. With technology moving forward so fast we still see manufacturers such as Apple using the socket on their products. Other connectors come and go like many fads the most reliable and easy to use connectors last. That's why the good old 3.5mm mini jack is my personal best.
Picture: Evan-Amos, Wikipedia