[cm2187]

I would have thought the main issue would be screen size. Don't developers like large screen real estate, being able to see documents side by side, or the code of your app, a browser rendering it and the debug tools inside the browser, and stackoverflow on the side?

[LyndsySimon]

It depends, mostly on preference, but also eyesight (and therefore, age).

My main dev machine is a 12” MBP. I have external monitors, but do quite a bit of work even on my 9.6” iPad. I spend 9% of my time in a terminal anyhow, and have good eyesight.

[saagarjha]

The parent comment asked to put aside hardware issues, so I left this out.