Thin and sharply shaped strings have the highest launch angle for me in a tight 18x19 pattern. Results may differ in a more open 16x19 pattern.
I've played with both Firewire Boost and Big Spin and neither was impressive to me. Firewire Boost was let down by how mushy the cross strings felt (I probably should have strung them tighter) and Big Spin had numerous shear breaks in the middle of the stringbed. Both strings changed their playing characteristics a fair amount as the pointy tip of the triangle wears down, which happens relatively quickly. Over time, the wear makes it behave more and more like a thicker and thicker round string, with lowering launch angle and lowering spin capability.
Highest launch angle strings I've found have been the sharply square strings like Ultra Cable, Rock 'n Power, or Cube.