UFO - Tell me what I need to know

You must get:

Force It
No Heavy Petting
Lights Out
Strangers In The Night (which I don't have)
 
Here's what you should get:

1974 - Phenomenon [first album with Schenker it has the original version of "Rock Bottom and the album is great!]
1975 - Force it [The sleeve was banned in the US. Great album!]
1975 - No Heavy Petting [Even better highlights include: "Can You Roll Her", "Martian Landscape" and "On with the Action". An underrated album in UFO's history]
1976 - On With the Action [Live album without the title track!]
1977 - Lights Out [Seen by many as their best studio album. I bought it when it was released. Very good album]
1978 - Obsession [Good but not great. Still a must have Schenker shines on this one but the songs are not as good as on the previous albums]
1978 - Strangers In The Night [Their legendary live album. However don't start with this one. you'll appreciate this album much better if you already know the studio verions.]
1999 - BBC Sessions [Fairly recent release of several "Live in the Studio" recordings. Great sound quality!]

UFO was an amazing band in the 70s. Each and every one of these reconds is essential. Look for the releases that feature 2 albums on one cd. Very much worth having.

Let me know how you like the albums.
 
"Force It" is my favorite! Great highlights abound! "Let It Roll","Mother Mary","Shoot Shoot", "This Kids", plus many more. "Lights Out" is also one worth getting.