OP
accordfire
NIC are more recognized but e.g ELECSA are cheaper and if a client asks what is elecsa the answer is simple a scheme provider.
Personally I think NIC is more desirable if the intention is to work in industrial or commercial rather than Domestic.
But I'm sure others here will share there thoughts
ELECSA is the ECA's notification scheme for Part P.
NAPIT is an independent notification scheme provider.
NIC EIC runs its own "Domestic Installer" scheme.
Costs are probably around the same overall.
A lot of it will come down to who offers you the service you're most comfortable with.