I was several months shy of being implanted with the Nucleus Freedom, so I have the Nucleus 24 Contour Advance.
I chose Cochlear because of their 20+ year history as a company who deals exclusively with CIs. In addition, they have the largest customer base which allows for more dollars spent in the areas of research and development of CI technology.
Whether I contacted Cochlear by TTY or e-mail, I always received professional and courteous customer service. Their staff also put me in touch with several CI users in my area who had a similar hearing history to mine so that I could ask them questions about their CI experiences.
I chose the Nucleus 24 not only because of the features found on the 3G BTE speech processor (disposable 675 batteries that can be purchased anywhere, a built-in T-coil which allows me to flip a switch and talk on the phone with ease, Whisper setting which enhances softer sounds, a choice of slow and fast speech strategies), but also because of backward compatability for those who have older CIs. For example, even though the Freedom BTE is new technology, it is backward compatable meaning that people who have the N22, N24, N24C and N24CA implants will be able to take advantage of many features found on the Freedom including BEAM directional microphones, ADRO, 4 program slots and a water resistant case.
When selecting a CI, it's important to remember that you are selecting an implant that you will have for the rest of your life. When you pick a CI and are implanted, there's no going back. Choose the CI which gives you the features you want/will use as well as a company (whoever that may be -- Advanced Bionics, Med-El or Cochlear) you trust.