Price out a few decent name brand options and decide for yourself. Avoid the single piston caliper styles like the plague. One of the key advantages of hydraulic is dual pistons that retract away from the rotor and that move in and position themselves with a balanced push from both sides. Just say no to one sided brakes.
Outside of that you want to go with a decent brand name and then check on the reviews. Keep in mind that some folks can break a tree without thinking about it and are just ignorant so don't look at the bad reviews so much as now many bad to how many good each system has. If there's only a few bad ones then the system is good.
Also how long do you plan on keeping this bike? If you were jonesing for a new ride a year away it may be worth it to just move the switchover date up.