Which is better: 301 Redirect in my .htaccess file or a plugin like Redirection?

The .htaccess catches requests before WordPress is even started. That’s much faster than any plugin.
For a handful of redirects I wouldn’t install a plugin. You need that only in cases when the server cannot know the new address, for example if you rename permalinks (slugs) automatically (you shouldn’t ;)).

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)