I have tried the following GPS software, all legally mind you via my friend's who had purchased these:
TomTom7:
I was impressed by the fact of how smooth and flowing the software was, and ease of use. lacking up to date pois and maps is a con, but otherwise I liked it. the maps were from q2 2008
IGo8:
Eyecandy and TTS and usability are the perks of this badboy. Only problem is the lack of most up to date POIs on my part. Maps were from 2008
Navigon7:
This badboy has eyecandy, TTS, Lane assist, but the latest maps were from Q2/3 2008.
lastly,
GarminXT:
this baby I ended up purchasing for myself. Will always have the latest POI list because of the use of Google for free, as well as traffic. My maps were from the city navigator 2009.11 update, so this has the latest map info, and POI list. Only drawback is lack of TTS, but honestly I'd rather have access to almost every POI at my fingertips then a pretty voice mispronounce my street HAHAHA.
My advice, try garmin
Hope this helped a little