So, I got a Wii Component cable.. and I'm really impressed. See rather basic comparison photos against regular old Composite playing a GameCube game. I'd recommend a cheap Wii+Component (£20+£7) over GameCube+Expensive
Amazon.com: HD Retrovision Wii/Wii U Premium YPbPr Component Video Cable : Video Games
Wii RGB vs Component, Advice needed : r/crtgaming
Mario Kart - RGB SCART TO HDMI vs Wii Component - YouTube
PS2 Component vs S-Video : r/crtgaming
Wii Vs WiiU Vs Gamecube Vs HDMI Vs Composite Vs Blunty - YouTube
N64 - Composite vs S-Video vs RGB Scart : r/crtgaming