If you’ll be playing with both hands (and in real time), then you’ll want a full length (i.e. 88 note) keyboard. If you’ll usually be playing with one hand with the other on your computer keyboard, then get something with 49 keys. I’m sometimes doing one thing, sometimes the other (depending on the nature of the task), so have both. If you’re a reasonably capable player, you might want the same.
A two octave keyboard is too short for most purposes and will involve switching octaves too frequently. 49 keys isn’t too long to have on one’s desk and when playing with one hand, octave changes aren’t needed that often. I’d recommend getting something that isn’t too deep from front to back (like a Roland A-49 - it has a socket for a sustain pedal) and not bothering with lots of pads. If your monitor or monitors is/are mounted on an arm rather than on a stand, you’ll have more space to play with. A keyboard like this doesn’t have to stay on your desk: it will weigh very little so just put it on there when you need it. You can then optimize the layout for other activities.
If you’re not too fussy about the feel of the 88 note keyboard, get something like a Studiologic SL88 Studio (which has aftertouch in case it might ever be useful, and four sockets for pedals). I’m in the UK but usually order from Thomann.