Your question needs some clarification. There are controllers for the VSTi, which controls parameters from the Plugin. There are controllers that control the DAW. There are controllers that can control the DAW and the VSTi or VST in case of effect.
I am using Novation Launchkey. Works pretty good, 49 touch sensitive keys and touch pads. I use the touch pads for drums. But it can also be used to launch in Ableton. If you're into EDM, you may want a performance type controller.
Point I am making, not a straight forward question. Let us know your objectives and then we can help.
Thanks for the info ,
soft synth are used mostly as VSTi, AAX if on Pro Tools,
and the number of parameters to manage seems to increase as new versions come out,
so a useful thing to know could be what controller has the highest number of presets ready to recall when needed,
or with the easiest way to create the templates-presets, like the "Learn" option as on Ableton Live,
as long as the Soft Synth supports it, although it should be a must,
the best thing would be that when the Soft Synth window is opened by mouse click,
also the controller load the relative preset-template,
without having to manually call it on the controller,
another important thing is that it is equipped with a good number of controls,
rotary encoders, switches, etc.. ,
to avoid having to change many pages for go from one parameter to another,
other things could be an appropriate number of displays to the number of controls
for the optimized "where i'm" user-operator interfacing,
and the led rings on the rotary encoders, unless the parameter value-level is visible on display,
being that it would be equipped with rotary encoders, switches, etc..
it could also work as DAW controller for volume, panpot, mute,solo, aux send levels, etc..,
something like a multi mode,
as some controller like those by Avid, Mackie, Icon, etc..., have been doing for some time now,
but which they do not offer an optimized section for Soft Synth
which can also be used for more classic plugins like compressor, eq, reverbs,etc..,
with at least 24 rotary encoders (3 rows each with 8 "slots")
each slot with a rotary encoder, 1 or 2 switches, and a display
that show the name of parameter on upper row and the level of it as horizontal line on lower row,
like for example on the Akai Mpc-X,
a unit to place on the desk aside the cotrol room monitors unit,
or in the center in front of the DAW computer keyboard,
another use of it could be as an editor-remote control of hardware synths
if mappable with midi CC controls and other similar, and store the patch-template in an internal memory,
so the more versatile it is and the more the type of use and users too increases as well,
an additional way of use could be as hardware old school stand alone sequencer,
that various manufacturers put back on the market in the form of relatively small boxes,
but with an extended number of parameters and options digitally controlled,
then if equipped with the option to switch between programmable remote controller and sequencer modes
would the number of users not increase further ?
(as well for manufacturer too...)
Or maybe just a point of view.