If you are just planning on a simple Head unit and four speakers these are my recommendations.
For the 3.5s in the dash the Infinity Reference series coaxials are very detailed and clear, Clarion also has some nice sounding 3.5" 2 ways.
Before you take them and just throw them in, I recommend you pick up a couple bass caps for the 3.5s. The bass caps are a couple very small capacitors that filter out lower frequencys passively, they are cheap and any good audio shop will carry them.
For the rear 6X9's don't bother going out and spending a bunch of money on the finest ones you can find, all these need to do is create lower frequencys for the system, the front 3.5's will take care of all the mids and highs.
Go out and pick up a pair cheap 1way 6x9s, no tweeter or anything fancy just a woofer cone, get one from a good manufacturer like Pioneer or Kenwood, a low grade manufacturers speakers will have poor build qualitys and sound bad.
This setup will give a better sound stage up front with half ass decent bass using just the headunit as a power source.
For a head unit it is somewhat personal preference, I like Pioneer, Kenwood and Clarion. when shopping for one just make sure it does what you need it to do for the right price.