I agree. Use AL32UTF8 database character set for Arabic. Use it for any language. All other character sets are legacy.
A question mark usually indicates incorrect client configuration. Try SQL Developer first. It should behave pretty well with Arabic even though some GUI areas may have problems with right-to-left writing. Then, you can try other tools. If they are Windows GUI-based and use OCI, set NLS_LANG to .AR8MSWIN1256 in Registry. SQL*Plus in Command Prompt will not work well with Arabic, if I remember correctly. It can display some simple queries but I suppose it will have problems handling right-to-left writing.