Your question brings another question with it, namely: what exactly would you like to achieve.
As pointed by @Gordon_Strange above, your use scenario will dictate what kind of midi controller you may employ. The one he points you to is a good solution for on-the-fly mixing, for instance. You can map faders to one of the mixers on the Mod and slowly add/subtract effetcs, for instance.
Other units like this one from Akai will have rotary encoders, faders, transport buttons, and pads for beatmaking (plus a step sequencer). You have plenty of controls to assign within the Mod and also trigger beats or other sounds. Moreover, you can assign midi notes and convert them to CC messages. Other options like Novation Zero line (now discontinued but easy to find used) offer the same minus internal generators.
If instead you need to toggle effects and synths, then you have Launchpad-like units that you can use with your hands, or else floor boards for foot switching. The Behringer FCB1010 is possibly the most used one, but I recommend one of the alternative firmware. Roland FC 300 is another option, and if you’re lucky you may find a Yamaha MFC10.
Or else, for more advanced and fine control the Softstep 2 from Keith McMillen has the ability to do both switching and modulate without an expression pedal, thanks to its X Y controls on each switch. (I haven’t tested it with the MOD to check if xy assignments are possible, fyi.)
Therefore, first examine what use you will have for a control surface – that is, what aspects/functions you’d like to command – and the controller will come to you. It might be the case that you will need more than one, but you can combine a 5-pin and a USB one, or else more than one USB with a dongle.