I think both did their fair share of good tunes. To make things easier, I'll list the most memorable ones:

Robert Allen
- Tubelectric
- Medivo
- Letni
- Orbitus
- Marbelara
- Crysilis
- Stonar (the longest in-game song next to the theme)

Alex Brandon
- Labratory
- Jungle
- Inferno 1
- (-) (you know what it says )
- Haunted House