The only two flaws the PS2 had, imo, were the dreaded DRE and its relative lack of power compared to Gamecube and Xbox. But with its stellar games, you didn't really miss the added power all that much. DRE, on the other hand, that really ticked me off. My launch console didn't even make it six months. I remember being on the phone with customer service (this was before it became a a thing and Sony lost its lawsuit), holding the phone up to the console so the woman on the other end could hear it squealing like a dying dolphin due to the laser mis-reading haha. It wasn't until the Slim dropped that I finally rid myself of that generation's RROD .

Still, it was the best console that gen by an eon and a half. It wasn't even close. 

It was a tough call for me between the PS1 and PS2 but my PS1 list would only consist of Final Fantasy and Resident Evil so for the sake of variety I go with the PS2.

1. Final Fantasy XII
2. Silent Hill 2
3. Metal Gear Solid 3
4. Castlevania Lament of Innocence
5. Shadow of the Colossus

Side Note: Konami was such a beast in that era. Hard to imagine nowadays but they were top notch in the 90s and 2000s.

PS2 was also dreadful with textures. They were blurry as hell compared to the other 3 systems which used pretty high res for the time. .  PS2 also was horrible with jaggies. I didn't like how so many PS2 games had a greenish hugh to them.

Much prefer how Gamecube,DC,Xbox rendered games native to that their hardware.

For me, even if I have only played a few games made for the system, the PS5 takes the crown.
I never liked the feel of the original playstation controller. It felt pointy in the palm of my hand while playing and the shoulder buttons strained my fingers a bit when used. The controller was basically the same in feel on PS1, PS2 and PS3. I skipped the PS4 so cannot say alot about that controller. But the feel of the PS5 controller is near perfection.

The PS5 with its subscription services is a gold mine for someone who didn't have a PS4. Almost all of the games I wanted to play on the previous system is included in PS+ so I have used it to play a lot of the gems I missed out on the past generation. The UI and feel of the menu make it very convenient for me to use. The sound of the system menu is so soothing that I sometimes turn it on just to have that sound in the background while doing other stuff.

When it comes to the games I have not played that many made for the system. Mostly replayed classics and games released for PS4. But the potential for the system is higher than any other console from Sony. And my first impression of it floors any other home console.

1. The last of us (PS4 verison, remaster of a PS3 game, played on PS5....Still the best)
2. It takes two
3. Elden Ring
4. Kena Bridge of spirits
5. Astros playroom

Can't vote the PS2, it's the only SIE console I never owned.

So the PS4

I have liked every PlayStation console except for PS3. In fact, I think PS3 is the worst console from the big 3 ever made, tied with Wii U.

I enjoy my PS5 immensely even though the library is not that great yet. But the OS, extremely fast loading times, and the fact that almost every game runs at 60fps, and improves most PS4 games as well, is awesome for me.
PS4 had a very good selection of games and got rid of all the problems PS3 had.
I went through a gaming hiatus during the PS2 era, but I can obviously see how good the console and its library was, and enjoyed a fair share of games later on.
PS1 was an absolute game changer, I loved the fact that I had an N64 and most of my friends owned a PS1, such a different approach and library, awesome to be able to enjoy both sides.

Ultimately I vote for PS5 because of the BC, making it essentially a beefed up PS4 and a PS5 in one.

Also:

Star Wars:  Knights of the Old Republic 
Jade Empire
Fable
Shenmue II
Ninja Gaiden: Black
Elder Scrolls III

I voted the PS3 because that's the one I spent most of my time with, but we all know that the PS2 is king.

I'm probably going to have to go with the PS2, if only for the sheer number of exceptional games the console had, but the PS1 and PS4 could have just as easily been number 1, and I think the PS3 is great as well, at least as far its game library is concerned, but perhaps the weakest of the four overall.

Top 5 PS2 games would be:
1. Shadow of the Colossus
2. Final Fantasy X
3. Metal Gear Solid 3: Snake Eater
4. Persona 4
5. Okami

And just because I can, here's my top 5 for the PS1, PS3 and PS4 as well.
PS1:
1. Final Fantasy IX
2. The Legend of Dragoon
3. Final Fantasy VIII
4. Final Fantasy VII
5. Grandia

PS3:
1. Dark Souls
2. Valkyria Chronicles
3. The Last of Us
4. Dark Souls II
5. The Legend of Heroes: Trails of Cold Steel II

PS4:
1. Bloodborne
2. Dark Souls III
3. Uncharted 4
4. Horizon: Zero Dawn
5. Nier: Automata

Surprised so many people are voting for PS5. Granted the console has been out for just 1.5 years.. and from current releases. There's hardly any big hitters, especially when compared to older PS consoles..