There's practically no series that I spend so many months and hours on. Sims might have compared between Sims 3 & New Leaf. Or something like GTAV. But I love Persona, Fire Emblem and GTA. Those probably accrue similar amounts of hours.
PS4 | PSVR | Switch
I would say the Pokemon series has more love from me than Animal Crossing does, however, I truly believe this site had a lot to do with my love for Pokemon. When Gen 4 was first released, this site could've easily been a Pokemon Wifi forum as well, and I got to play and trade with dozens of people. Pokemon Gen 3/4 has aged the best imo, having great pixel art and timeless gameplay. When it comes to newer games, I'd definitely prefer Animal Crossing. Even though Animal Crossing is a 20+ year franchise, it has yet to lose it's charm. Pokemon on the other hand has been faced with some consistent criticism the past few years, some of which I ultimately agree with.
Animal Crossing: New Leaf | TLOZ: BOTW | Metroid Samus Returns
For me, Animal Crossing is more of a good comfort game when I’m in between other games and is usually the constant in my gaming library at all times. My favorite video game series are the Ace Attorney series, the Persona series, Legend of Zelda, and Metroid. I also really love Stardew Valley and go back to that one quite a lot!
Animal Crossing: New Horizons, Fire Emblem: Three Houses, and Genshin Impact
As a few other people have mentioned I'm a big fan of Stardew Valley as well alongside AC. I'd also say Bravely Default is another series that I love a lot, as well as the Hamtaro game series oddly enough (the GB/GBA games are surprisingly good for being based on an IP!)
Other than that, while their playtime is definitely dwarfed by the amount I've played AC (which is many, many hours ), I'd say Psychonauts and Night in the Woods are two other games I hold a lot of love for!