I use a 20.1" LCD on my main Amiga, 4:3 aspect ratio, of course. 99% of Amiga software is designed for this ratio (actually I've heard it's 5:4, but 4:3 is close enough).
On my 500 at home I use a 37" widescreen display. I can either stretch it or live with the vertical black bars on the sides. Normally I live with the bars.
I've played around with just about all the resolutions and aspect ratios my Spectrum and Indivisions are capable of, and these are just what I prefer. My .02 cents.
