Titanium Backup vs Android data backup
I think you're better off using Titanium Backup if you want to ensure that when you restore your phone, you'll have exactly what you had when you performed the backup.  I find that Android's new built-in backup options are inconsistent.  For example, after re-installing some apps, some of the settings are magically maintained, however some data (usually authentication data) is no longer there.  I guess this is a good thing as storing everything in the cloud would be a bit scary, but when you use Titanium, there are no surprises: all of the data is restored.

Another benefit of Titanium is that you can do multiple backups at of a single app's data and restore any of those levels--not so for the built-in backup options.

So I'd advise using Titanium.