In my experiences with delving into a band with as large a discography as their reputation, it's always best to start at the beginning. Seems easy enough, but the problem here is there is four or five different iterations of Pink Floyd as band members came and went in as the members changed in themselves as well.
Piper at the Gates of Dawn and A Saucerful of Secrets, the first two albums, contain my two favorite Pink Floyd tracks, "Astronomy Domine" and "Set the Controls for the Heart of the Sun". Piper has two versions, so I'm not sure where you are listening to these albums, but the UK version contains the aforementioned "Astronomy Dominae", while the US version contains "See Emily Play". "Emily" is the only chance we get to see a love some from Syd Barrett while with the band. "Interstellar Overdrive" is another notable track on Piper. Saucer has a few more Syd Barrett tracks, and brings in David Gilmore. This album gets pretty Space Rock and is a great listen, but brings us to the end of the first Pink Floyd.
More is a soundtrack for a film by the same name. The album is good, but I have a hard time considering albums that were made in conjunction with another piece of art as a part of the band's Canon.
If you listen to these albums in chronological order, like I've suggested, Ummagumma is next. Feel free to skip the first disc, which is just live versions of things you just heard. The second disc here though, is a different Beast. Essentially each member made of tiny album on their own. It's a bit of a trope but it gives us insight as to where each band member is coming from, and what they are bringing to the table. It also helps us understand who's doing what in other songs later. Atom Heart Mother brings an end to the second iteration of Pink Floyd. The album is great, but there really isn't a great Stand Out track from it.
Pink Floyd The Third is the Pink Floyd we all know and love. Meddle, obscured by clouds, Dark Side of the Moon, and wish you were here. Meddle is less cohesive then other albums in this phase because the band is still trying to figure out this new thing and everyone worked on lyrics which didn't lead way to good flow. Echoes is definitely the takeaway track on this album. Obscured by clouds is definitely the lesser of this phase of Pink Floyd though it's still a decent album. Dark Side of the Moon is their most commercially successful album and is super cohesive. Alan Parsons (the guy who wrote that song I love to sing at karaoke Eye in the Sky) was the sound engineer for this album and you can hear it if you're familiar with his other work. He also worked on the Beatles Abbey Road and let it be. Wish you were here is fantastic as well. Every song on the album is played on the radio. No small feat!
Rodger Waters pretty much took over after wish you were here this is where I'd say the 4th Pink Floyd comes around. Waters' Pink Floyd. Animals is good but super different from previous works. It's massively political critiquing the social political conditions of the late 70s Britain the album was released in 77. The wall was again political but Less in your face about it and also delves into it issues like abandonment and isolation. It's definitely worth a watch of the movie as well. The Final Cut Is the last album Rodger Waters worked on and then claimed that the band was finished. Again political this album hits on interpersonal conflict and war.
With Rodger Waters leaving the fifth generation of Pink Floyd began. This phase brought us three albums, a momentary lapse of Reason, The Division Bell, and the Endless River.