from personal experience,
supercharger seems to be harder to make power and it isn't as efficient...
again, this also comes down to the right sizing of turbo/supercharger and in turbo side of things, a big roll is played by the exhaust manifold...
quick example...
a ap2 s2k I did for a mate, with SOS supercharger kit (stage 2kit) made 240kw on 12psi
my bros k20a2 s13 silvia with a custom exhaust manifold and gt3076r on 12psi made 290kw

both cars on same dyno, same tuner and same pump 98 fuel

the s2k did see 270kw with e85...