TouchOSC is the most used MIDI controller in my setup if we don't consider the MIDI keyboard itself. It has been around for a long time. It's cheap, cross-platform, and has greatly improved my workflow, allowing me to set up keys that run Cubase/Nuendo macros or Project Logical Editor commands.
A few helpful buttons
My original template in the older version of TouchOSC (called Mark I now) has several pages that allow me to navigate my chunky orchestral template in Cubase. The Cubase template is divided into four macro-areas (Woodwinds, Brass, Percussion, Strings). Each of these areas is a top-level folder, containing a structure made of instruments and articulations. I programmed buttons on TouchOSC, for example, to "hide everything but one section", or "hide everything but an instrument".
Most people working with big orchestral template will know that if you are not using keyswitches or other forms of switches, each articulation is a different MIDI channel and, hence, a track in a DAW. So it is very easy to reach a large number of tracks in a project. I know people who compose on templates with thousands of tracks via Vienna Ensemble Pro. My personal experience is that, most of the time... a lot of these tracks will be empty. There's no way that you're going to use all the First Violins articulations (pizzicato, spiccato, staccato, marcato, portato, trills, tremolo, just to name a few) at the same time. So, another useful button I set up is a button that "toggles visibility to all unused track". This way I don't have to get crazy scrolling all the way up and down among chasms of unused lines. Only tracks with events will be visible.
Not everybody works in the same way. That is why it is important that you build your TouchOSC template around what you think is going to be more beneficial for your workflow. I cannot stress the importance of this enough. TouchOSC is a powerful tool. You can do almost everything with it, in conjunction with macros in your DAW. If you start by creating buttons for everything, you'll never see the end of it. So, my suggestion is to be aware of how you work, and how you could automate the most recurring tasks.
In my case, I found out that my recurring operations are really just a handful:
Colouring selected tracks
Moving selected tracks to a folder
Setting/going to markers
Toggle unused tracks
Toggle "Automation follows events"
The ubiquitous Undo/Redo
Fold/unfold each section/subsection folder
Read and Write automation
Record Enable
Transport controls (Previous, Next, Loop, Pause, Record, Click)
There are also a few other tools like a jog and a nudge wheel, vertical and horizontal zoom, a more general fold/unfold that will work on both folders and MIDI/Audio tracks to open automation lanes, up and down cursors, and a section for Cubase/Nuendo's assignable Quick Controls. In my case, most of the time I use QC1 as Modulation and QC2 as Expression.
The "Markers - Colors - Macros" buttons open different layers (called aptly "containers" in TouchOSC). Here is the top of my Macros page (it spans the same height as the Colors tab in the template). Most of it is still blank but when building the template I imagined it could grow in scope over time, so I left some space where I am sure new buttons will save me endless right clicks.
Out of the top of my head - the next ones that I will add will be "FX Channel to selected channels..." and "Group Channel to selected channels...", but I am sure there will be more. As I "evolve" as a producer and composer, I realise a few operations will change priority, others will be abandoned, new ones will emerge. So my suggestion is to allow the TouchOSC template to undergo the same evolutionary process.
Helpful considerations when you are building a TouchOSC template
Try to put everything really important in the first page of the template. If you need to go through the template to find the right button, it's no use: touches should be less than number of mouse clicks!
Enjoy colours! Enjoy shapes! The later versions of TouchOSC offer a lot more control than the original Mark I. Be funky.
Build stuff with an eye to the future. One of my previous mistakes was to create Cubase PLE functions such as "Hide/Unhide FLUTES", which obviously searched for the string "FLUTES" in the folder names, and then toggled visibility of that folder. Yay, genius! But why if you're recording a rock band and there are no flutes, glockenspiels, LASS Divisi, or whatnot? You're screwed. So I made names more generic, such as 100, 110, 120... until 590 in my case. This way, I can just add "100" in the name of a track to allow my functions to localise it without being instrument-specific.
Be modular: this goes hand in hand with the previous point. Build buttons, macros, PLE functions, so that they are generally applicable to a lot of scenarios, and leave room for upgrades. That could be even in the name of the function. As mentioned, I had a "Hide/Unhide FLUTES" PLE function. Over time, it became apparent that hiding tracks would not work for my particular taste, and folding/unfolding would work much better. So the problem with the naming was not only the "FLUTES" bit, but it turns out it was also the "Hide/Unhide". Which I then replaced with a more general "Toggle".
A few tools will make your life easier, depending on your DAW. Sadly the PLE in Cubase has a few instructions that are in hexadecimal format, but there's nothing stopping you, after you created a working PLE function ("Toggle 100"), to make copies and automatically rename them with the free Bulk Rename Utility ("Toggle 110", "Toggle 120", "Toggle130", etc.), and then open the hex part with the free Visual Studio Code editor and modify only the "100" number with something else. I used VS Code also to open Cubase/Nuendo XML files that store macros, key commands, etc. Be creative and you'll save time in making hundreds of little adjustments in minutes rather than hours.
Conclusion
There is more than one way to take advantage of TouchOSC. I personally use it as a MIDI controller just because I am a Nuendo-based kind of guy. Its real power, though, is harnessed when used as an OSC controller (clue was in the name). I am looking at you, Logic and Reaper users. If properly configured, there is a hell of a lot more information that you can send and receive using OSC.
Make no mistake, even if you use it only as a MIDI controller you have plenty of operations that you can program, but OSC would allow you to even print the channel name that you have currently selected in Reaper or Logic on the template. Fun!
I find that TouchOSC has less latency when my tablet is connected via a USB cable - but that's only necessary if you are using faders to control your DAW session in real time. In my case I have two scenarios: when I compose on the DAW, cabled connection is fine; when I am recording live instruments or voice from the recording room, I connect TouchOSC to an internal, dedicated router, and can press the Record, Play, Pause buttons from one room away. That is an awesome feature if you, like me, don't want necessarily to buy a purpose-built remote control.
Finally - if you have any questions about how to build or integrate TouchOSC to have a better workflow in the studio, ask away! I'll be happy to give a few pointers.