GTOZ. No contest. If you can't afford one, try a Ryobi 3302, or even it's predecessor the Itek. Printers the world-over bought either of these presses and produce CMYK to great effect.
Main points are - good register system and true 2 colour printing. Don't consider a Printmaster or anything like that. Common blanket presses will start off looking ok but after a few sheets have gone through, the ink starts to migrate and contaminate the light colour. You might not notice it until it's too late.
Rolling power is important too. GTOs have 4 form rollers per unit and the inking is far more forgiving as a result. It's easier to maintain colour.