For me, the best NES emulator is NEStopia UE, which is absent in recent builds.
I really don't know how it works, why old version has disappeared from repo?
I trid building it myself running "PROJECT=Amlogic DEVICE=S905 ARCH=arm scripts/create_addon game.libretro.nestopia"
but got an error during compilation
../libretro/libretro.cpp:1:10: fatal error: libretro.h: No such file or directory
I believe it's because of moving libretro.h from "nestopia/libretro" to "nestopia/libretro/libretro_common/include" in this github repo - GitHub - libretro/nestopia: Enhanced version of Nestopia for Linux, BSD, and Windows
I don't have programming skills to make PRs so did some things for myself.
I found that a commit in the github - kodi: update binary-addons/emulation packages · LibreELEC-AML/LibreELEC.tv@adfeae4 · GitHub
Reverted changes in packages/emulation/libretro-nestopia/package.mk and packages/mediacenter/kodi-binary-addons/game.libretro.nestopia/package.mk in my local copy, and then compiled addon with
PROJECT=Amlogic DEVICE=S905 ARCH=arm scripts/create_addon game.libretro.nestopia
and got this file - Yandex.Disk
I installed it, and it works!
As for SNES, I use Snes9x 2010 Emulator. It works with most games' i've tried.