I would recommend "Open Range" as it covers a lot of the melodic strengths of Kamen and is just so beautiful and heartfelt music. It also has some nods to his previous scores (including dead zone) but I think that's because he had to score it on short notice, replacing another composer;
Incidentally, X-men -another replacement score- also recycles a bit of Dead Zone with the school theme but I would recommend experiencing dead zone in the movie prior to listening to the album, same with his Die Hard score(s).
Henry, here are my top 5 Kamen (I tend to prefer his melodic side on album, though his action scores are usually effective in-film):
1. The Iron Giant (just brilliant and beautiful) 2. Band of Brothers 3. The Adventures of Baron Munchausen 4. Don Juan de Marco 5. Open Range
I also like Robin Hood and Three Musketeers but not as much as these. And I'll second the recommendation for From the Earth to the Moon. Kamen and other composers wrote GREAT music for this miniseries and I hope LaLaLand puts out a box set of it for us sometime soon!
Kamen's Shining Through is one of his absolute greatest scores. A beautiful lyrical theme for piano and full orchestra in the classic Kamen sound, some haunting intimate moments throughout, then great suspense, and an intense climactic action. Really one of the purest Kamen scores.