I'm really glad I did Global Unity before I tried the other NIA tapes. It definitely has the best production values and is by far the most modern of the tapes.
Roots is another copyright 1991 tape. Same set, similarly scary outfits. The music is a little funkier in parts, but still Firm-ish. Debby leads this one, and it's a lot more grounded (hence the name, "Roots." ) I didn't watch that much of this one, but it didn't make me want to jump up and do it.