Basically I'm new to playing but I'd like to learn a number of chords etc. possibly learn how to play from the bottom upwards, 45 keys sounds more convenient for space, but 61 seems to be the minimum size that many would go to. Thoughts?
I was in a same boat not that long ago.
And I went for 61 keys and never regret it since.
Yes it takes some serious space(I have Novation Sl MK2 61) and needs a stand but it really makes a difference cuz I am not touching octave shift buttons that much and can play with both hands without any problems.
You will quickly learn basic triad chords, it is not a rocket science.
But for more advanced chord voicings stuff more keys will be more convenient.
I am learning jazz stuff now and improvization with both hands takes whole keyboard sometimes. So my vote goes for at least 49 keys if you want to actually play keys.
But if you are going to play only with one hand to, for example, sketch chords or for very basic stuff, 25-32 keys will be enough.
I bought a 25-key one originally and grew out from it in about 2 weeks when I decided I want to play bass and chords simultaneously. I'd also suggest 49 ->, 61 is probably the smallest _actually_ playable. I got a 76 key Kurzweil now and its fabulous.
I started with a M-Audio Axiom 49 which I liked since it had the 49 keys, but ever since I've bought a second hand Roland JUNO-D I haven't touched the Axiom anymore. Those few additional keys are so great!