Garbageland

edge emulation (missing some consoles; CD-based games come in compressed formats such as CHD; very fast DL speed)

myrient (pretty much everything, no strings attached; fast DL speed)

cdromance (mostly has games for CD-based consoles; games come in uncompressed iso or bin/cue; has a lot of pre-patched rom hacks; medium-fast DL speed)

planetemu (largely in french; has a lot of obscure titles other sites lack; very fast DL speed)

alvro collection spreadsheet (pretty much everything, including many newer consoles; slightly inconvenient to navigate; download site has timer and limits to 1 download every 30 mins, can be worked around with vpn; inconsistent medium-to-very-fast DL speed)

script that lets you download from emuparadise post-shutdown (pretty much everything; inconsistent medium-to-very-fast DL speed; can occasionally be uncooperative)

ROMs Megathread/Archive (everything, really; slow DL speed; usually a last resort if you can't find something anywhere else)

i don't currently recommend Vimm's Lair due to very slow speeds, download limits, and offering nothing that isn't on other sites (unless you need prepatched xiso format Xbox roms)

console-focused sites:

HShop (all 3DS. very complete, easy to navigate. has qr codes for direct download from 3ds; yes, the qr codes are safe; fast dl speed)

MarioCube (focused on GameCube/Wii and has everything you'll ever need for those platforms; requires joining a google group for standard roms but it takes like 2 clicks; very fast dl speed)

NoPayStation (practically every PS3/PSP/Vita game and update, downloaded directly from sony's servers; fast dl speed)

sites offering switch and other modern games get shut down very frequently so i won't be linking them in order to keep this post from getting outdated, but you can find them if you snoop around reddit (the switchpirates sub in particular) a little

romsets:

Cylum's Romsets (my personal favorite - not fully complete sets but heavily curated, so no going through a million revisions of the same game)

for 1fichier directories, you can use a tool like 1fichier-dl to download in bulk. i'd recommend doing this on the alvro collections if you want more complete sets.

softmodding and loading roms on some popular consoles:

Switch

Wii

3DS, Vita, Wii U

PS2

PSP

recommended emulators and emulation guides:

Emulation General Wiki

netplay:

wanna play with your friends online?

fightcade covers nes, genesis, pc engine, dreamcast, and snes along with a variety of arcade boards from capcom, snk, sega, and konami. playstation is incoming. all platforms on it have rollback netcode.

mednafen covers psx, saturn, pc engine cd and sega cd, and i find its snes performance better personally. delay-based netcode with server structure. here's a pre-packed version with a gui included and here's a netplay guide i largely wrote myself.

other than that, dolphin is naturally used for gamecube/wii, and project64 with the AQZ netplay plugin is used for N64.

games are great. go play some games.