Please recommend the best portal GPS for my car (to $600)
 

I see so many new models available on the market - from Garmin nuvi to
garmin C330
c340 seems to announce street names
c530 does not announce street names, but it is newer, acquires
satellite signal better and has a non-glare screen
there's Tom Tom One that some people say is great
there are some Magellan models - they provide GPS devices to Hertz and
the one I used in a Hertz car seemed to be working fine.

Can someone help figure out what is really the best portal GPS out
there? I plan to only use it in my car.

Thanks.