Deleted

1. Battle Net <PC Client> (as a blizzard fan, that enjoys each game as it is, my favorite one)
2. Steam <PC> (Majority of my collection gets re-bought to keep it centralized and auto-updated, modding / workshop content doesn't seem to grow as fast as it did when it was unofficially supported / looking at you old Half Life mods)
3. GoG <PC Client> (for my older games that don't exist anywhere else / but are re-bought if they ever appear on steam)
4. Epic Game <PC Client> (Unreal Tournament, Paragon, Unreal Engine)
5. Nintendo DS <console> (Classics like Advance Wars, and Pokemon, etc)
6. Sony PSP <handheld> (ps1 classics collection, as well as my favorite games such as metal gear acid / metal gear and card game whats not to like)
7. Sony Playstation One <console> (all my favorite games were on this beast, Command & Conquer, Armored Core, Metal Gear Solid, Diablo, Final Fanasy VIII, Granstream Saga, Grandia II, Mass Destruction, Ace Combat 2, Air Combat, Army Men, Test Drive Offroad, Bomberman Party Edition, Cool Boarders, Dance Dance Revolution, Dead or Alive, Driver, Duke Nukem, Dune 2000, Einhander, Fear Effect, Fighter Maker, Galaxian3, Gran Turismo, Gunship, Lego Island 2, Lego Racers, Machinehead, Medievil, Metal Slug, Mortal Kombat, Loaded, Maximum Force, Mechwarrior 2, Moto Racer, Myst, Namco Museum, NFL Blitz, NHL Blades of Steel, Nuclear Strike, Resident Evil, Parasite Eve, Tempest X3, Quake II, Rampage World Tour, Risk, Road Rash, RPG Maker, SimCity 2000, Sim Theme Park, South Park, South Park Rally, Soviet Strike, Space Invaders, Spec Ops, Steel Reign, Strider 2, Strikers 1945, Syphon Filter, Tales of Phantasia, Tekken, Theme Hospital, Theme Park, Thrill Kill, Time Commando, Time Crisis, Tom Clancys Rainbow Six, Tomb Raider, Tony Hawks Pro Skater, Twisted Metal, Vagrant Story, Vigalante 8, Warhammer, Warzone 2100, Wild Arms, Wipeout, Wizardry, Worlds Scariest Police Chases, Worms, Xmen vs Street Fighter, Xenogears, etc) <after listing this, I think i need to pull my CD archive out and bust out my system from my storage>
8. Origin <PC Client> (How else am I going to play my Battlefield and Command & Conquer games?)
9. SNES <console> (Classics like earthbound, super mario world, etc)
10. N64 <console> (Classics like Starcraft 64, Paper Mario, Goldeneye, etc)
11. Gamecube <console> (Classics like: MGS Twin Snakes, Custom Robo, Phantasy Star Online, etc)
12. Dreamcast <console> (Classics like: Resident Evil Code Veronica, Aero Wings, Blue Stinger, Phantasy Star Online, Gundam Side Stories 0079, Love Hina, Shenmue, Virtua Fighter, Slave Zero, StarLancer, Sonic Adventures, Crazy Taxi, Dead or Alive 2, Ikaruga, Power Stone, Soul Calibur, Virtua Cop 2, Wacky Races, Worms World Party, etc)

EDIT
To put this list in perspective I actually own the following consoles and have the following clients installed on my PC:
Atari 2600
Atari 5200
Atari 7800
Nintendo Entertainment System (NES)
Sega Genesis
Super Nintendo Entertainment System (SNES)
Sony Playstation (PS1)
Nintendo 64 (N64)
Sega Dreamcast (DC)
Sony Playstation 2 (PS2)
Nintendo Gamecube (GC)
Microsoft Xbox (Xbox original)
Microsoft Xbox 360 (X360)
Microsoft Xbox One (XBO)
Nintendo Gameboy (original phat version)
Sega Game Gear (GG)
Nintendo Virtual Boy
Nintendo Game Boy Advance (GBA)
Nintendo DS (DS)
Sony Playstation Portable (PSP)

BattleNet Launcher (Blizzard Entertainment)
Epic Games Launcher (Unreal Dev)
Origin (EADM / EA)
Uplay (Ubisoft)
Glyph Client (Trion Worlds)
Windows 10 Store / Xbox (Xbox Play Anyhwhere)
Stardock / Gamestop App
GOG Galaxy
Desura / One Play

Other Devices in my house that I can play on:
Sony Playstation 3 (PS3)
Sony Playstation 4 (PS4)
Sony Playstation Portable Vita (VITA)
OUYA <no longer here>
Nintendo Wii <no longer here>

Steam and Battle.net (Overwatch) :)
Sometimes AC Syndicate, The Division and Far Cry Primal on uPlay.

Steam,_,

steam only, no money to buy consoles and pay for games there.

Mainly GOG, followed by Steam