Honestly, I'm a bit biased since I'm such a big DOOM/id/Retro and retro-style FPS fan, but Doomguy is my most-wanted candidate for Smash, at least in terms of third-parties. Not only would he make for such a cool and unique character with a interesting moveset in Smash, but if it weren't for his home series, the game industry of today would probably look a lot different. DOOM has influence many things, such as the birth of the FPS genre, the PC being made into a significant and influential gaming platform, the rise of the modding scene, and even the debate on violence in video games. It also helps that the series has a significant history with Nintendo; not just with DOOM 2016 on Switch and DOOM 64, but also the SNES and GBA ports of the original games which were technical showpieces for those two platforms.
If Doomguy gets into Smash, I want trophies and music from various games in the series, from DOOM 1 to DOOM 64 to DOOM 3, then all the way up to DOOM 2016 (and possibly DOOM 5 if the release is close enough and Sakurai and his team are given pre-release materials from id). Not only that, but why not give some minor Quake representation? It would be metal to hear tracks like the Quake 1 theme (
https://www.youtube.com/watch?v=Mv5Jvr2Fp48), or Descent into Cerberon from Quake II (
https://www.youtube.com/watch?v=ALBKFB28E0M) sometimes play when fighting on Doomguy's home-stage. Also, Quad-Damage power-up please.
So yeah, consider me a supporter.