I am planning on getting new door speakers for my car and i was thinking about the alpines or maybe infinitys but I'm not sure. What are some good brands?

Depends on you price range, but a set of Alpine Type R speakers are the best bang for your buck....without a doubt the best sounding set of speakers you can get for under 250 dollars

You can run them off your head unit but you wont get the bass you want. A small alpine amp (i use an older Alpine V-12 75w x 2 amp to power two Alpine Type R 6x9s. Its sounds so good i got rid of my 12" Concept sub-w) will give the speakers the power they need to perform the way they were designed to. Any speaker will distort and sound crappy if you try and drive them hard off of the head unit alone.