Eric, I pretty much concur with just about everything said here.
First thing to do is analyze your needs and wants.
Have a look at your dive profiles, environment and particular tasks if any, both what you've been doing so far and the diving you want to do in the future.
Then have a close look at the rebreathers that are available, make sure you understand how they work. What they will and will not do. Try to match the rebreather to what suits you.
It's really not easy as there plenty of offerings today, new and used, and all of the above suggestions to consider. While the broad variety of rebreathers will probably get you pretty close to perfect you may well end up modifying your choice (or at least wanting) to get yet another bit closer to that perfection you seek.
