Of the premium Apps I prefer Mapquest over Telenav, it's only 49.99 per year and it stores the map data on the phone so you don't need data connection the whole time you are enroute. Telenav requires data connection at all times. Both are great programs and offer free trials, so try them both out and see what works best for your needs.
Blackberry Maps and Google Maps are both nice free options, but neither give you voice guided directions.
There is also a free program called aMAze GPS, but I wouldn't recommend it at this time. Maps lag, making it practically useless. Also I have found quite a few inaccuracies in the map data itself here in Indiana. Turn by turn mode works better than map view (faster) & voice prompts are crisp and clear. Who knows, maybe the map data is more accurate where you live.
Also there is an application called Nav4All that I have not tried, but I understand it to be free also. No recommendation one way or the other on it, but I have included a link.
Links: http://www.mapquest.com/features/slashmobile_navigator Voice directions on your GPS phone: TeleNav Google Maps
Go to this link from your BB Browser and download Blackberry Maps OTA: http://mobile.blackberry.com http://www.amazegps.com Nav4All - Free gps navigation for your mobile phone!
I hope the links help.