I have been using Altirra for quite some time now and I think it is great, you download .atr files at http://atari.vjetnam.cz/index.php?frame=games and there you will find more games than you can count. . . . . . .
If you have used this Emulator please let me know what you think. . . . . . .
This is not one that I've used. I may check it out.
I did use one called Xformer and it wasn't bad but Altirra is way better. . . . . . .
I'll have to check it out, then.
I listed all these amazing emulators in the Atari Visual History book withe pros and cons, but yes. Altirra is more or less king of the hill