When considering a rebreather, look at the support that comes along with it.
For example, if you are traveling, get to your destination and find that
something was damaged during shipping, can you find the part(s) to repair it,
locally? This plays a big part and the major reason I went with the rebreather I am using.

What type of chemical is used to scrub the CO2? Is the chemical in a canister that is easily replaced so you may continue your dive with minimal surface interval or is it the granuals which you must pack?

How long do you intend to stay down, contiguously?
How deep do you plan to go?
Whose electronics are being used to manage gas flow, can it manage multiple gases? Decompression? Is it customizable, easy to read and understand, user friendly. Does it manage the selenoid or leave it up to the diver (manual).

How much are you willing to initially invest?
How much are you willing to invest on a dive basis (ie. scrubber, diluent, O2, bailout)

Are you willing to invest the extra time and effort to maintain the unit before, during and after a dive?

These are just a few of the thoughts that come immediately to mind.
Personally, I believe rebreather is the future of diving. Getting into now will set one up for the wave to come. It's just a matter of time.

Good luck on your adventure...