Page is still work in progress, more content will be added overtime.

The following consoles below have AV output by default and can be improved by using additional mods.

Nintendo Consoles

Ranging from NES to Wii.

NES consoles

Original Famicom is the worst, both AV Famicom and NES top loader are the best models after getting modified with better AV outputs.

NES Original

Standard outputs: RF and Composite
Additional outputs by mods: S-video + RGB and HDMI

https://www.game-tech.us/mods/original-nes/ http://voultar.com/index.php?route=product/product&product_id=50&tracking=

Notes:
It's currently not possible to mod both RGB and HDMI onto a single official NES due to size of the chips and even if it was possible, it wouldn't be able to output both analogue and digital at the same time.
This is because analogue runs at 60.08hz whilst HDMI runs at a tad slower 60,00hz. It may not sound like much but certain games like Super Mario Bros, that is is a huge deal.

NES Top Loader

Standard outputs: RF only
Additional outputs by mods: Composite, S-video + RGB and HDMI

http://www.retrofixes.com/2014/05/nes-101-toploader-av-mod-kit.html https://www.game-tech.us/mods/original-nes/ http://voultar.com/index.php?route=product/product&product_id=51&tracking=

Notes:
It's currently not possible to mod both RGB and HDMI onto a single official NES due to size of the chips and even if it was possible, it wouldn't be able to output both analogue and digital at the same time.
This is because analogue runs at 60.08hz whilst HDMI runs at a tad slower 60,00hz. It may not sound like much but certain games like Super Mario Bros, that is is a huge deal.

Original Famicom

Standard outputs: RF only
Additional outputs by mods: Composite, S-video + RGB. But not HDMI due to size.

http://etim.net.au/nesrgb/installation-famicom/

AV Famicom

Standard outputs: Composite only
Additional outputs by mods: S-video + RGB and HDMI

http://voultar.com/index.php?route=product/product&product_id=51&tracking=

Notes:
It's currently not possible to mod both RGB and HDMI onto a single official Famicom due to size of the chips and even if it was possible, it wouldn't be able to output both analogue and digital at the same time.
This is because analogue runs at 60.08hz whilst HDMI runs at a tad slower 60,00hz. It may not sound like much but certain games like Super Mario Bros, that is is a huge deal.

SNES models

Original big SNES models support RF, Composite, S-Video, RGB and HD Retrovision's Component cables, but they have poor boards that makes the games look less sharp.
Per Tim Worthington (creator of the NESRGB): "The original Super Nintendo/Famicom video chip does low pass filtering on the RGB video before it gets out to the pins. The 1 chip version doesn't do this, that's why the video from this console looks better.
I don't think replacing the video driver circuit would make any difference."

Later models are always guaranteed to have later 1Chip boards which mean sharper pixels. Sadly, the console only supports composite but after it gets modified with S-video/RGB your SNES will look fantastic on CRT tvs.

SNES Junior models

Standard outputs: Composite only
Additional outputs by mods: S-video + RGB

http://voultar.com/index.php?route=product/product&path=60_62&product_id=61

N64 models

Nintendo's first console to only have 1 model throughout but the motherboard did have a few alterations during its life cycle.

N64 NTSC

Standard outputs: RF, Composite and RF
Additional outputs by mods: RGB and HDMI

http://voultar.com/index.php?route=product/category&path=60_63 http://www.badassconsoles.com/ultrahdmi/

Unlike the NES, it's possible for a single N64 console to support both RGB (HD Retrovision Component cables for SNES should work) and HDMI.
It's also possible to display HDMI footage on LCD TVs and Analogue footage on CRT Tvs at the same time

Gamecube

A small reminder that the console's region disables one av option and enables another.
S-video only works on NTSC consoles.
RGB SCART only works on PAL consoles.

Gamecube PAL

Standard outputs: RF, Composite, Component and SCART
Additional outputs by mods: HDMI (internal or plug in external)

http://www.badassconsoles.com/gcvideo/

Notes: PAL released Gamecube games do not support 480p by default, you have to run Swiss and turn on Force 480p, then with your overpriced component cable or HDMI (after it is modified) you can play it in clean 480p quality. Another way is to by NTSC versions of your favourite games and just hold the B button when starting up a game and say YES to enable progressive mode.

Gamecube NTSC

Standard outputs: RF, Composite, Component and S-Videos
Additional outputs by mods: HDMI (internal or plug-in external)

http://www.badassconsoles.com/gcvideo/

Wii

Nintendo's most successful console and the first to have 3 models released worldwide. Small tip, avoid the red Wii Mini at all costs.
Similar to Gamecube, the software bios region settings disables one av option and enables another.
S-video only works in NTSC mode.
RGB SCART only works in PAL mode.

Original (2006) and Family (2010) Wii systems

Standard outputs: RF, Composite, S-Video (NTSC), SCART (PAL) and Component
Additional outputs by mods: HDMI, not to be confused with cheap Wii2HDMI adapters

Notes: Still work in progress so no link available.

Wii Mini (2013)

Standard outputs: Composite only
Additional outputs by mods: ... no idea.

Notes: It doesn't support GC games, GC controllers, SD Cards and online for Wiiware/VC games. Avoid this console at all costs.

SEGA Consoles

Ranging from Sega SG-1000 to Dreamcast.

Will be added later.