Motec is better from a technology point of view, but from a doing the job point of view , GEMS is probably a better fit. GEMS can use a MAF or MAP, has idle control and knock sensor. Motec is MAP only I believe, has no idle control (although you can get a box from Prospeed to sort this out). Motec also have a very good argument against knock sensors (too long and complicated to go into here). GEMS is quite good value for money. Link is an option, but not as advanced as either of these IMHO. Autech is also another option.
Can I ask what you are trying to achieve first (i.e. what problem you are trying to solve) before suggesting an ECU or modification?