Final Fantasy VIII is my N1 on the PS1. One of my all-time favorite games for its characters, its gameplay and its unbelievably gold-tier soundtrack.

Here's my top 10 just for fun:

1. Final Fantasy VIII
2. Metal Gear Solid
3. Castlevania: Symphony of the Night
4. Resident Evil
5. Crash Bandicoot
6. Diablo
7. Final Fantasy VII
8. Silent Hill
9. Tekken 3
10. Resident Evil 2

Never played any of them, but Crash purely because of the wacky characters and commercials. Unfortunately because I know his voice actor I can't hear PS1-era Dr. Cortex without expecting him to talk about Krabby Patties.

Xenogears, even if it was just the one game.
But, on the list Final Fantasy: Specifically FF7, 8, and Tactics.

My favorite today is Metal Gear Solid or Tekken 3.
Tony Hawk was fun and still is fun but not on the same level as Metal Gear Solid and Tekken 3.

Enjoyed Crash Bandicot and Spyro back in the day but I did not like them at all on a revisit. The story on how naughty dog pushed the PS1 to its limit to get the game running is compelling.

Shoutout to the PS1 version of Diablo that has a special place in my heart since it was translated into Swedish. Hearing the blacksmith with a local dialect and the Butchers catch-phrase always brings me a smile.

Resident Evil 2 (my personal fav PS1 game)
Metal Gear Solid
Final Fantasy 7
Resident Evil 1
Klonoa
Doom 1 & 2
Worms
Resident Evil 3
GTA 1 & 2
Random Demo Discs (remember those :D, has to be said as most of my happiest PS1 memories were these)

CTR is my favourite game of all time.

The Crash and Spyro series on PS1 are it for me.

I've only played so many PS1 games even with emulator, but best ones so far are Revelations: Persona (Persona 1) and Gran Turismo 1, followed by Dragon Warrior VII, FF8 and Ridge Racer Type 4.

PS2 favorites Okami and Ratchet & Clank 2: Going Commando.

Best game: Castlevania: Symphony of the Night. By far. My next PS1 favorite would still be a distant second.

Best series: Definitely Resident Evil.

I would have thought Metal Gear solid would win hands down, not just cause it's a great game but it's one that defined how the industry shaped itself for years after. It brought about cinematic story telling in games for better or worse and while often worse it just goes to show how ahead of itself it was.

Best series has to objectively be Final Fantasy. But my favorite series was Resident Evil, followed closely by Syphon Filter. 

The best game is probably Metal Gear Solid, though. I mean... what a masterpiece.