Novation 61SL MKIII
MIDI Controller by Novation with 61 keys, easy to use sequencer, arpeggiator, customisable templates for multiple devices, lots of knobs and sliders, and some DAW integration I'm not fussed about. Pretty close to my ideal keyboard-based controller—just more keys, polyphonic aftertouch, ability to send SysEx, and not needing software to do configuration would make it perfect. The MKII covers the SysEx and no software side of that, and I'm half-eyeing a Zero as an addition, but not sure if I actually need SysEx at my fingertips like that…
You have to use the Componants browser tool to do some of configuration, especially customise you instrument templates, as well as firmware updates. In Firefox and Chromium it keeps losing the USB connection or something when sending and receiving data (tried on both Linux and Windows), but standalone version (I think it's an Electron thing]] has versions for Windows and Mac that work fine. I haven't got it to run in Wine. The downloader feeds you the download based on you browser's user agent, so to get it on Linux you have to use an add-on to set it to Windows :/ I grabbed the first one I found and it worked fine: User-Agent Switcher by Linder.
Found a Python alternative that's supposed to use json files for templates, but it seems to have been abandoned before it was finished: inno/slmkiii.
I haven't tried it yet, but this is supposed to be a better-than-official way to use it with Reaper:
'App for creating System Exlusive messages to adjust the displays on the SL mk3 keyboards': https://github.com/cbradburne/NovationSLmk3-SysEx
Uses 12V 1A centre positive power adaptor. Standard 5.5mm / 2.5mm plug. I'm using a 2.1mm and it's fine.