I've heard a lot of people label "Echoes" as Pink Floyd's "greatest hits album." But as we know, PF were never a hit single band except for their early 2 Syd-singles and of course 'Another Brick 2.' "Best Of" and "Greatest Hits" are not the same thing, because a band can have a song that is their best yet it never had chart success or better yet was never even released as a single.
So, after some research, I've compiled a list of Floyd's studio songs that would show up on an album designed strictly for the songs with great to minor chart success.

1. See Emily Play
2. Arnold Layne
3. Money (#13)
4. Another Brick in the Wall Part 2 (#1)
5. Run Like Hell (#53 on the Pop Singles chart)
6. Not Now John (reached the UK Top 30)
7. Your Possible Pasts (#8 on Mainstream Rock Tracks chart)
8. The Hero's Return (#31 on Mainstream Rock Tracks chart)
9. Learning To Fly (#70 on Billboard Singles #1 Mainstream Rock)
10. One Slip (#5 on Mainstream Rock Tracks)
11. On the Turning Away (#1 Mainstream Rock Tracks)
12. Take it Back (#23 in the UK)
13. High Hopes (#7 Mainstream Rock Tracks)
14. Lost For Words (#21 Mainstream Rock Tracks)
15. Keep Talking (#1 Mainstream Rock Tracks)
16. What Do You Want From Me? (#16 Mainstream Rock Tracks)

Any others with chart success anyone can think of?