New Machine specs

I am returning to this list after a year or two as I am returning to
CNC. I have used a self converted sherline for several years and now
wish to move to a larger machine.
I am thinking desktop with a square column (V-ways). It should have
reasonably accuracy using the original lead screws and be somewhat
simple to convert.
My question is what machines will fit this and which motors,
controllers, power supplies will work with the least 'tweeking'?
Is it better to motorize the quill or the whole head, neglecting the
weight issues?
Thanks, PJH