Für die Entscheidung welcher Datentyp für euch am geeignetsten ist würde ich die SQL Referenz empfehlen (Character conversion)
The CCSID value for data in UCS-2 format is
13488.
UCS-2 is a subset of UTF-16. UCS-2 is identical to UTF-16 except that
UTF-16 also supports combining characters and surrogates. Since UCS-2
is a simpler form of UTF-16, UCS-2 data will typically perform better
than UTF-16.