Oh shit. This was most of what I did in my childhood and during my mid to late 20's, just retired the hobby this year. I'm starting to miss it, but there has to be tens of thousands of hours I won't get back. My list would be all over the place.
My favorite classics are Tetris and Joust. Super Mario Bros 3 is awesome.
My favorite 16 bit titles would be Zombies Ate My Neighbors, Smash TV, SMW, Chrono Trigger, all of the Dragon Quest games are awesome, and though it's not well known, I loved Haunting Starring Polterguy, it was unique and there's still nothing quite like it. Both versions (snes and genesis) of Shadowrun were favorites of mine as well, same with the Beavis and Butt-head games that were completely different. While those cover the game systems of that gen, it was at the tail end of it that I remember using my dad's computer to start playing games. I remember the joy of using ms dos to boot Doom. Holy shit. What a time it was going from those console titles to something like that. Doom will always be a favorite of mine, even earlier this year I was playing newly made wads. System Shock and its sequel were the next pc titles to stand out for me.
Favorite 5th gen titles would be Metal Gear Solid, Silent Hill, Xenogears, Mario 64, and Gran Turismo 2. While not necessarily a favorite, I always thought LSD: Dream Emulator was a bizarre but interesting concept.
Favorite 6th gen titles would be Morrowind, Silent Hill 2-4, Soulcalibur 2, Eternal Darkness, Metal Gear Solid 2 and 3, Katamari Damacy, Fable, Gitaroo Man, Psychonauts, Okami, Chulip, Manhunt, and GTA 3.
7th gen contains my all time favorite title but this gen also murdered a few of my favorite series and started what I see as the downfall for me personally. This gen lead to the always online, dlc infested, fuck huge updates, p2w, loot box garbage that plagues AAA publishers now and killed my desire to keep up, but hey, at least there was huge surge in independent development teams. My all time favorite game is Left 4 Dead, I loved both titles and nothing has ever given me as much fun in a team setting, it was perfect for me. I really enjoyed Oblivion, Fez, Hotline Miami, Bioshock 1 and 2, Dark Souls, Fallout 3 and New Vegas, Super Mario Galaxy, GTA4, and the Portal series. This is also where I finally picked up Pokemon. I started with Black 2 and it remains my favorite entry. I immediately got sucked into breeding for IVs, abilities, natures, and egg moves, while perfecting ev training depending on what move set I'd use. Sadly, sword and shield ruined it for me and I don't look back.
I owned an xbox one and switch but I just found myself playing the old games I liked. I can't think of many 8th gen titles that stood out to me. I played a lot of Elder Scrolls Online. The new State of Decay game was okay I guess, as was the enhanced version of Dying Light. I just kind of lost interest. At this point I mostly played indie pc titles like Project Zomboid, Factorio, Space Chem, (I'm just now remembering the Talos Principle and Antichamber), Rimworld, and I'm sure there's others I can't thin of right now. I remember playing a lot of The Sims from 1 to 4 but I mostly just treated it as an architect simulator. Also have a soft spot for point and click games. The Cat Lady and Fran Bow are my favorites as far as modern titles, favorite classic is probably I Have No Mouth and I Must Scream. 7th Guest and The 11th Hour were great classic puzzle games. I really enjoyed some rpg maker titles, namely Yume Nikki and all the fan games that followed. I should really stop here. I apologize for this wall of text that no one will read through, and if you made it, thanks. Gaming was always a staple in my life. I couldn't possibly make even a top 5 right now, but I think I can put Left 4 Dead at number one with Pokemon Black 2 coming in a close second. The silent hill series would likely be third, hard to divide them. Yeah, I need to stop.