But, the better 3rd party brand lenses tend to be better than the Nikon and Canon cheap kit lenses. I don't have any experience with the Tamron lens Anbesol recommended, except that it has a good reputation as one of the better 3rd party zooms.
For portraits and weddings, it will be more than built well enough. I dont own the 28-75 myself, but I've played around with it quite a bit and it is impressive, the perfect focal range for portraits, and the perfect f-stop.

And of course, it *blows away* any kit lens you throw at it.