The main types of automatic gearbox are: torque-converter (aka a traditional automatic gearbox), dual-clutch, CVT and automated-manual. Torque-converter and CVT gearboxes are generally the best for long-term reliability, although cars with CVT gearboxes can be noisy during acceleration. Dual-clutch gearboxes are generally very quick to change gear, but their complexity means some are unreliable in the long-term. Avoid automated manuals as they're often jerky to drive.