Audio stuff is all personal preference. So it all depends on what you like and how much you're willing to spend. Have heard anything you like? Or have an idea of what you might like? The options with audio stuff are endless.

Here's a link to what I have.
http://www.toyotanation.com/forum/3...-gen-corolla-2nd-gen-matrix-interior-audio-forum/765106-stereo-my-10-5-gen.html

 

I added a pioneer double din with nav. Changed the look of the interior so much

 

I want to replace all my stock speakers, as they are garbage on my car, the owner before me had mentioned that when he tried to do something with he audio he f'ed it up. I also want to get a touchscreen nav in my car as well. For the speakers I just want better quality at a fair price.

 

I replaced all my speakers with alpine type S. I've used them in the last and always worked perfect for what I needed. Did components in the front. I also got this alpine amplifier brick thing that came with my radio. It is a small amp that mounts behind the radio. Really changed the sound of the speakers. Then I got a pioneer double din with nav. I spend $400 for the nav and the alpine amp thing off of Craigslist, 25 for mounting and wiring kit. And about $200 for the speakers

I have 2 extra brand new mounting kits if you'd want them. I'll sell them really cheap. I have metra and scosche. Sell them both for $15 shipped if your interested. This was you can see which one you like better