I would recommend a Compustar or a Viper (or any DEI Product).
Here are some links:
Stay away from cheap brands like Bulldog (Walmart special). They are a pain to install and program and won't last very long.
Ungo is a little better but I still would go with something a little more expensive.
Remember that with all car electronics including stereos, you get what you pay for.
BestBuy or any good stereo shop will have better models. They range in price depending on what features you want/need (2-way, alarm combo etc.).
Are you planing on doing the install yourself or are you paying to have it installed ?