In no particular order:
Pokémon
Megaman (Classic/X/Zero/Legends)
Metal Gear
Castlevania
Metroid
Gradius
TMNT
Super Mario
Final Fantasy
Spider-Man
I realized while making this list that most of the franchises I had listed I only liked one or two games in the series. Kingdom Hears for instance I used to be addicted to, but, while I enjoyed the time I spent playing 358/2 Days, I mainly like the first two games. And this resonates with StarFox, I like the GCN games, which I've yet to finish, but the SNES and N64 games are my all-time, and possibly only favorites. Drakengard is another favorite of mine, but so far the first game is the only entry in the series I've completed and haven't even made the effort of fully trying the sequels. Same from the likes of Armored Core, Contra, Metal Slug, and Zelda. I also wanted to include Gundam in the last slot given I have a slew of games from the series that I've enjoyed some way or another, but my love for Spidey conquers mechas.
I enjoyed Arceus enough for what it was, but Sword/Shield and Scarlet/Violet are so crazy bad, it's really hurt the series for me.
I'm more the opposite, where I'd put Scarlet/Violet near the top if I'm ranking Pokemon gens. While the games were janky at times, I enjoyed the story, characters, open world, and many of the new Pokemon. My main nitpick would be that I wished the game had better level-scaling as it could get too easy to overlevel and it would've fit the open-world aesthetic better if the gyms all got stronger as you progressed (e.g. Larry would have a stronger team if he were the 8th gym you faced than if he were the 5th). Sword and Shield however, I would agree with them being terrible and would rank them near the bottom.
Objectively speaking, Scarlet and Violet aren't up to snuff in technical terms what with the myriad of bugs, glitches and what-have-yous that infest the games; I'm certain at some point in time while playing you must've witnessed an oddity or two. Quite frankly, anybody who says the contrary is either lying or downplaying their actual experiences; we're all playing the same game after all. Personally, I'm enjoying the game, I truly am, no BS; this was the type of game I wanted way back when I was in school discussing the future of the series with my friends during recess and we all giddily opined how cool it would be to go from place to place and see actual Pokémon while traversing, going up to them to initiate a battle or just to watch them. The way we discussed and described the game we wanted out of the series was basically what an open world game is today, which wasn't even a thing in those days. Simply put, Scarlet and Violet were my dream game come true, and I'm happy that I lived long enough to see it through, it truly is an amazing feeling to have. But, once again, objectively speaking, the games aren't without their faults; they needed to be in development for at least another year, period. Game Freak bit more than they could chew.
It's sad to see the world's most profitable gaming franchise that's nearing 30 years in the market release a game in the state they did, and even sadder is that still to this day they continue to be a diamond in the rough, far from ever reaching their full potential. I love this series, I can't leave it no matter how hard I try, but it would be futile of me to try to cover the whole sky with the palm of my hand. They're business model is running the franchise to the ground, I feel.
Even though I had my doubts, which I expressed somewhere around here, I pre-ordered Scarlet. The last time I bought a Pokémon game on its release date was Diamond and Pearl, which I also pre-ordered; Gen. V I sadly missed out on due to personal issues, but I eventually got them; Gen. VI and VII I got after the fact since I wasn't optimistic with the jump to 3D, and I've yet to play any of them; Gen. VIII I still haven't got, although I intend to at some point down the road if and when I find the version with the DLC at a reasonable price. All that to say come the next game in the line I'm waiting it out; I still enjoyed Gen. VI–VIII without actually playing the games.