Hello all,
Not sure if this is just old news, but the LAKKA OS seems, to me, to be the best way to view/manipulate Atari roms. Meaning, the roms aspect ratio can be changed to almost anything you want. Being able to play any Atari 2600 Rom, in a 16:9 aspect ratio in full true HD, gives you the best modern viewing experience for these games. I play the roms, thru the Lakka OS, which is installed on a modern Intel PC as the sole dedicated operating system. Although the latest Atari Flashback 8 HD does a good job as well, the aspect ratio of the games is not great as they don't fill the screen. With this emulator, you can even view box art while flipping thru your list of games. If you like to experiment you can install the OS on a Rasberry Pi, or eqivalent, and fit it inside the original case of an Atari 2600. For more information see the site below.
http://www.lakka.tv/
Enjoy!