It depends what exactly you want control and how you want switch synthes (if at all). It is hard to give advise till that is known. F.e.
- you want control fixed parameter set in one (or more) fixed plug-ins (f.e. synth 1 parameter 20 + synth 5 parameter 96 + etc.)
- you want control synth (or FX) in focus
- you want select the synth from the device (so, be able to switch from synth 1 to synth 2, etc)
Or something else...