This is dependant of your personal preferences.
there are a lot tranings from different Vendors
SAP is offerin Training for Basis,
but keep in Mind Basis consits out of Operating System, Database, and the central Applikation.
Basis is an good choice for the future, but an strong continuos Training is needed – Java may be the future – and even if Basis is not offering an job you can specialise to any Application in the enterprise bussines.
Infos which are also availiable in english:
Good luck and best success