Hi debasah,
Recently, I tested M 147 against U87 Ai, and ended up buying the latter... To my ears, the M 147 was too bright on sybilants, and considering the fact that I mostly record people singing in Polish (LOTS of ssssssssssss), I went for U87 Ai.
However, Neumann themselves suggest M 149 as your first choice for lead vocals and background harmonies (U87 being second). So if I had the money, I would like to test M 149, too.