Emulation for Atari 2600 and NES

[JudgeRob]

Hi,

I am sure this is somewhere, already but I can't get the search function to work...

For these systems, are separate emulators recommended or should I use MAME to run emulation?  I read that MAME was making progress in other systems, but I can't tell if it would be better to use something like Stella.

Atari 2600:  Stella?
NES:  ?

[DarthMarino]

I've been using Mesen for NES and have been happy with it.