I don't care for the first Tubeway Army album, or Replicas to tell the truth. I've got so used to hearing the Replicas songs played live that when I go back to the album originals, they sound a bit basic. It's still a great album though but I think the idea is stronger than the music itself, as the songs have since evolved through being played live.
I would certainly recommend everything from The Pleasure Principle to Warriors. I always liked Warriorss, it has some great tracks. Dance is good although it took a while for me to warm to it. It's much more experimental and unusual.
Mid 80s Numan isn't as bad as its made out to be, once you pick out the best bits and there are plenty.... The Hunter, Cold Warnings, God Only Knows, The Pleasure Skin, The Sleeproom, My Breathing... and the entire Metal Rhythm album which I think is excellent. It has a more commercial rock feel to it, but it is really well produced and contains some super pop tracks it's a differrent kind of Numan, altghough still a million miles away from Telekon or the other early albums.
If anything I would avoid Outland and Machine and Soul. However not all of Numan's early 90s output was bad check out his instrumental albums Human and The Radial Pair which is excellent, and paved the way for oe of his greatest and darkest albums, 1994's Sacrifice. One of his most "Numan" albums.
1994 present has seen Numan's revival and a change in direction to a heavier electronic/industrial sound. Sacrifice, Exile, Pure, Hybrid and 2005's Jagged are all worth checking out!!
Hybrid was an interesting project, taking old Numan songs and reworking them with various contemporary producers.