In the studio I tend use combinations of this setup most:
Live 9: When doing EDM, DJ, loopy sort of work
Presonus Studio One v3: When recording and mastering.
Logic Pro X: I've got lot's of history tied up in this app but I tend to use it less and less these days .
iPad Air 2: Either tethered and connected to USB Audio or over WIFI as a remote controller for Studio One.
iPad Pro 2nd Gen: Tethered to USB Audio with a 2m lighting cable.
Soundcraft Signature 12 Mixer: 14 USB audio i/o + 12 channel analog inputs, solid, reliable and very simple to use.
For audio i/o from the iPad I used to use StudioMux a lot, but nowadays I use Apple's built in USB Audio connection, creating an aggregate device in Audio MIDI Setup which is then assigned in the DAW. That way I can stream the audio from the device to the Macbook with no hassle and pretty low latency.
Various old keyboards and MIDI controllers which I've collected over the years including a MIDI retrofitted Mini-Moog and a decent size Eurorack analog synthesiser with 5 x 104hp rows of modules which is for another story altogether!
When Playing on stage:
I like to keep this as simple as possible...
For a master piano controller I use an old weighted keyboard made by Doepfer, it has no controls but feels lovely to play.
For MIDI and lead synth control I often use a an old Yamaha CS2X, I like this keyboard but I rarely use it's internal sounds these days but it has 8 dial controllers for MIDI on top of the usual mod wheel and bend.
Footpedals, sustain and expression, sometimes I add in a Behringher FCB1010 if I need extra control.
The FCB1010 is a great controller but sadly it's no longer supported so not sure how much longer I can use it.
My iPad is connected to an Apple USB Camera dongle which allows me to keep it powered on stage while using USB for audio etc.
For live MIDI connection I use a simple Roland UM-1, very simple very reliable inline MIDI socket.
The iPad and keyboards feed into an old Tascam mixer and from there to the PA.
Apps for stage use: Given I play in a Psy rock band, ( when I'm DJ'ing I use the studio setup ).
LayR: ( of course!! ) Lead synths, pads and FX.
AUM: I use IAA in preference to Audiobus, all apps feed into AUM with some my MIDI controllers assigned to the channel faders. That way I can mix my sounds in anyway I need with very little hassle.
Shoom: Synth Bubbles, Sirens, and all sorts of weird noises. Love this little app, simplicity and fun to use.
Various other apps, depending on the set we're playing: For Rhodes and Piano I like the IK offerings they're limited in their functionality but sound good. Sometimes I use Galileo for organ sounds. LayR has taken over from all the other synths I used to use!