The best compablitiy for the old and great demos(Sanity Art etc.) & games is achieved by an A500 with extra 512Kb and DD both with a switcher. (ON/OFF) Costs few euros today!
Then for the next software an AGA machine, mine used to be A4000 but changed to A1200 as it is really quite the same with cheaper expansions.
With a '060 You get a few incompabilities but it's more worth it than Your "When It's Done-Sign"
After the Picasso IV I have to use two monitors, dont know why? I have an old NEC-multisync for everything and from the old A1200 output an PhilipsCM- standard Amiga monitor as my C1084S used to be. Have to see for example the Early Startup Menu for this. Not Bothering me anyway..
The A1 is fast and the best! Don't really get this if You need a lot of old sofware but who cares? Works for me and never going to go back (but the A500 for retro).
Emulation is never been a consideration because I am an true Amigan and not this "pc-emu" - guys!
I know that I'm going to get some of the last comments, please excuseme of my bad english!
See You!