To add my two-penn'orth to the Hillage topic.  The dates/sequence are my
best guesses, and may be way off:

1973: Fish Rising
=================
Very Gong-like, an excellent album of whatever genre you would put old
school Gong into.  Spacey pysch with strong French, jazz and feminine
influences.  I think Fish Rising differs from Gong chiefly in having these
specific influences diminished by comparison.

1975: L
=======
Probably Hillage's biggest seller, but not my favourite.  Straightforward
spacey psych with a guest appearance from Don Cherry, IIRC.  Less Gong
influence, I think of this as one stop along Hillages' journey from Gong to
New Age to Commercial to Techno...

1976: Live Herald
=================
Not heard this but my interest was certainly piqued by the earlier posts in
this discussion.

1977: Motivation Radio
======================
Moves on from Fish Rising and L in that there are the first appearances of
Steve's pop leanings, and Miquette Giraudy has more influence.  As Nick
pointed out, the lyrics start to get more New Age, but overall a pretty
good album, essential for Hillage fans.  Hello Dawn has some nice flanger!

1978: Green
===========
My favourite.  A number of different kinds of song on this album, from the
funk of Unidentified Flying Being to ambient stuff.  But there is a
commonality running through it, consisting of the warm synthetic sounds
someone already mentioned.  Lots of vocoder and guitar synth.  THIS is the
album that has the Glorious Om Riff, i.e. a reworking of Gong's Master
Builder.  It has a nice change to the time signature.

1979: Open
==========
Awful attempt to go commercial.  There is one song I like on this album,
which might be Earthrise.  It sounds a little bit like the Police!  The
rest of it is dire, including Don't Dither Do It (it was never in any dream
of mine, y'see!)

1979: Rainbow Dome Musick
=========================
Lovely ambient stuff consisting of guitar and synth only.  A must.

1982: For To Next / And Not Or
==============================
The Open vein gushes in full flood.  I don't know the And Not Or album so
nothing to say about that, but For To Next is surely the most ill-advised
Steve Hillage record ever, and that includes the System 7 stuff.  Thin,
weak, vacuous....

System 7
========
Everything after 1982 I suppose.  Doesn't do it for me, I have tried
listening to it and it just makes no impression at all.  I suspect I am
turning into my father...

Steve