Here are twelve of my favorites, only one of which is in the top twenty most-downloaded installments. I can recommend them all both for the quality of music and the quality of sound. The first was the original inspiration for the Avant Garde Project and is still my overall favorite.
AGP2 - Mauricio Kagel, Acustica AGP44 - Mechanical Musical Instruments I AGP65 - Hans Werner Henze III AGP69 - Total Improvisation
AGP82 - 9th International Contemporary Music Festival AGP83 - Berio Conducts Berio AGP92 -German Orchestral Music I, 1980-82 AGP102 -Henry Kaiser, Outside Pleasure LP
AGP104 - Mauricio Kagel, Luc Ferrari AGP111 - Horatiu Radulescu, Clepsydra Astray AGP117 - Iancu Dumitrescu