Need help with car speaker upgrade?
Listen to speakers on display at a good stereo shop. Some will sound better than the ones you have. Those may be worth choosing. Consider how they fit in your car. Discuss that with the technician.
I know quite a lot about car audio because I do professional installs on the side. An upgrade to speakers that can handle more power isn't really going to do a lot of good for you unless you get an amplifier for them. If you are hearing distortion or static at a loud volume, it probably isn't the speakers (unless they are blown), it is usually due to distortion caused by the low power of head unit (radio). If you want loud, clean, distortion-free music, a power amplifier is a necessity. In fact, the stock speakers installed by the factory in a 2007 A3 are really pretty decent (Infinity Reference 6532EX. Look em up on Amazon), so unless they are damaged and buzzing, crackling, etc even at lower volume, I wouldn't bother upgrading them since they can handle 55 watts rms per channel. That is more than enough to hurt your ears if you have the amplifier to push them, and they have pretty decent bass response too. Your radio, at best, only puts out 22 watts rms watts max, and possibly less. That isn't even half of what the stock Infinity speakers can handle. I'd install an amplifier instead, but if you are going to replace the speakers anyway (send them to me, please) then you are going to need a shallow-mount type of speaker so they fit your doors. There aren't many choices better than what you already have unless you're willing to spend a lot of money. The best reasonably priced speakers are the JBL GTO629 which is a shallow mount design. They'll set you back about $90 a pair at Walmart, and $75 online at Newegg. They have a tiny bit better bass but can handle about twice as much power (again, only an amplifier could supply it)