My first question is when did the NDS and PSP become "retro"

?
And as for me... I'm never without SNES emulation. I'm a huge fan of RPGs and SNES has most of the best that were ever made.
Currently I am playing a Chrono Trigger fan hack called Crimson Echoes that fills in the story that happened between Trigger and Cross. Its like 98% finished or some crap - SquareEnix sent a cease and desist to the developers. You pretty much have to play with cheats or you'll die constantly because they never got the battle system tweaked properly. Even leveled at 99 and max stats, you will pretty much lose at least one character every battle when you get around the 10 hour mark in the game.
I hate ePSXe though... Its so damn finicky with plugins (on the PC anyway, I've never tried PS emulation on my phone). PCSX2 runs faster than ePSXe does and that's running PS2 games in higher quality than the original PS2. The developers were supposedly going to add on support for PSX games but I haven't been following the project.
What phones are you running these on?
I have the HTC One and it gets hot playing the SNES emulator (SNES9x+), I couldn't imagine trying for PSX on it. Kind of obnoxious really. It stops charging if it hits 109F.