Best Pokemon game

I've only played fire red and I want to play another game. Which one is the best that I should play?

idk I stopped playing Pokemon with White and Black and I legit don't remember anything from the series other than the show

SW/SH is my favorite pokemon game after XY.

I love Diamond and Pearl
The old crinkly graphics one
Haven't played the enhanced graphics one yet
Cynthia the GOAT

I'm a huge sucker for Emerald

I like Black and White. Best gen because it has Munna

bw2/emerald
hg/ss is okay, rest are slop city

since you dont have the nostalgia bump to get over:
Modern games are the best in terms of gameplay if you already have a switch (yes graphics suck, but qol does just improve steadily), so S/V

for an older one Id personally go with B/W or B2/W2
peak of top down pokemon both in terms of gameplay, pacing, dex (no old returning pokemon might be a turnoff though, but theres a TON of new ones since they had to fill an entire region) and art-style

ORAS GOATed

Scarlet and Violet are fun too, lots of QoL shit

sorry bro you already played the best one...

BUT I would recommend heartgold! Lots of fun, maintains the classic pixelated look but has more dynamic environments + better coloring/shading, you get to play in 2 regions, and has all the gen 1 and 2 pokemon plus some gen 4 ones. Also epic final boss (you will appreciate it since you've finished only fire red)

PokemonCrater. IYKYK.

HeartGold,

i pretty every pkmn game and HG is the best one, not close either

if you want the general consensus of of the pokemon community then the best games are Black/White, but in my personal opinion its Ultra Sun/Ultra Moon

Pokemon Ultra Sun/Ultra Moon for the overall experience
Pokemon Legends Arceus is the best pokemon game ever made imo, although its not a conventional pokemon game

diamond/pearl peak

SWSH

b/w 2, best games in the series by far

detective pikachu game
those who know: 💀💀

USUM is cinema

Heavily recommend USUM or Legends Arceus if you want something different.

If you want to stay in 2D, Platinum or one of the Black and Whites

Diamond/Pearl are slow and unpolished versions of Platinum

X/Y and omega ruby/omega sapphire my personal favs

b/w is the best gen but its such a generic pic imo

SS best game in franchise

If you're looking for a kind of a modern experience, OR/AS and US/UM are the best to me. If you're looking for a rather old-schooled one, I guess B/W is among the best because it doesn't have the slowness of D/P/P, and before DS games, they used typing to split up special and physical attacks which I don't like. It makes many Pokemon borderline unusable because of this
If you don't care about that then Emerald is great...
And if you're patient, Scarlet and Violet are worth to try out. They're objectively pretty bad games for today's standard and are absolutely hideous but are great on some other levels.

And if you're looking for an absolute mid tier and boring experience, your best choice is Sword and Shield.