MIne's a Martin D12-28 and I have a Kyser, Shubb and G7 for 12 string.

Of all, I find the best is the Shubb (mine's brass because I like the colour) for 12 string.

Yet the G7 (for 6 string) is the best by a country mile for my D-28 or 000-28.

FWIW.

Have fun