This question is like asking what's the best flavor of ice cream. Everybody has a different opinion based on different tastes.
You'll be fine as long as you go with a quality deck from a reputable manufacturer. Just pick the deck that best fits your budget with the features and asthetics you're after.
Check out the likes of: Alpine, Nakamichi, Pioneer, Kenwood, Eclipse, Sony, Blaupunkt, JVC, Clarion, Rockford Fosgate, Panasonic, etc... (I'm sure I've forgotten about a few too)
If you can give some specifics like price, required features (mp3, satellite, outputs, etc.), likes/dislikes, asthetic preferences, future system expansion, you'd get some better specific references.
