Emulators are usually produced by different teams. Sites devoted to emulation primarily mirror the files put out by the teams. So few sites are actually unique. The only two worth mentioning are Zophar's Domain and The Emulator Zone. Zophar's Domain is one of the oldest emulation sites on the internet, and has the largest collection of emulators, hex editors, sound rippers, and level editors around. The Emulator Zone is a bit smaller, but is still regularly updated, unlike Zophar's, which has slumped in recent years.
The best emulator is NO$GBA
Information for a n64 emulator can be found on sites that deal with console to PC emulation. Sites such as AlteredGamer, TheISOZone and PocketGamer (UK) have all the information on how to obtain a n64 emulator.
emulator-zone.com visualboyadvance is the best.
From my research, I have learned that Project 64 is by far the best emulator you can find.
there are many sites, no$gba its actually best nds emulator, try version 2.6a
The best PS2 emulator in terms of compatibility and relative speed is PCSX2.
The best PS3 Emulator can be found on the Emulator Zone website. The download on the site is called rpcs3, it is for Windows and is a free download. It has a 3.5 star rating.
Emulator sites don't normally have gamecube roms and a lot of emulator sites have been swarmed with viruses lately, It might be a better choice to buy the PC version of the game. If you still want to risk it, Emuparadise and CoolROM seem to have it.
nogba
no
Project64.
the best free emulator would be QEMU. But IEmulator V is a pay emulator that works amazingly.