Nokia has it's own app, but it's free: Here Drive+.
Yes, it monitors your speed and it chimes at me when I exceed the speed limits, but you can turn that off.
Now, I haven't fiddled with the voice, but I think that you can only choose a male or female voice.
EDIT: Fiddling with the voices now, they have every language known to mankind on here, but if you're only looking for an English accent... you can choose between the UK or US versions of male or female voices.
Nokia WP phones pack a great native GPS experience with Here Drive/Here Drive+. Pre-downloadable offline maps, good voices etc.