I find that my 170's LCD looks just as good as my Portable's. (Well, they did three years ago, anyway; the last time my 170 was out of storage, and the last time my Portable worked...)
The IIc Flat Panel Display was terrible. REALLY low contrast, insanely difficult to see. (Yes, I used one way back when it was new. My high school computer instructor had one to go with his IIc with battery pack; he later upgraded to a Macintosh Portable!)