My personal preference is for a 4:3 monitor. My Cybervision 64 with 4mb video ram can do 1280x1024 in 16 bit non interlaced mode but not at a sync rate that is usable on most monitors. 1024x768 24 bit non interlace is also a bit touchy but not as bad. It requires a monitor that can do a vertical sync of 56hz. 16 bit 1280x1024 works best at around 50hz vertical which most monitors can't do. My current Amiga monitor is a Cornea CT1702 which can do both NTSC and PAL--50Hz--frequencies on the 15 pin RGB port. It also has composite and s-video inputs which are handy for a video toaster. The lowest vertical frequency it can sync to is 48hz. It doesn't even blink when I switch from NTSC to PAL in scan doubled native Amiga modes.
To do 16:9 properly it would probably be best to program a custom video mode. The preset modes that come with Picasso 96 and Cybergraphix 4 are from an era when 4:3 was the standard. I've never owned a Picasso IV but a quick look at its specs says it can do 1280x1024 in 24 bit non interlaced which the Cybervision 64 can't do, so I think it would work better in 16:9 modes.
