I have a pioneer DEH-6050UB hooked up to a pair of jbl component speakers(comes with a pair of tweeters mid range speakers and crossovers) a pair of JBL ovals and a JBL 4 channel amplifier. Also got a 1000 watts pioneer sub in a box, the ovals are on a plank at the back and the components are in the front. The entire setup sounds really great in my swift. The sound is well balanced and the clarity is excellent!
Generally when going for a car audio system, its always better to go for a pioneer head unit, the quality is really good, its got great features, got a user friendly interface and also they are pretty good looking too! It would be a good idea to go for a head unit which has sub woofer controls and an equalizer since it makes configuring it easier, not to mention the usb direct connect option.
When going for speakers you must avoid pioneer speakers because they are very poor nowadays, back in the old days when pioneer speakers were made in japan they were really good, now they are usually just made in china which are of poor quality. Preferable you could go for JB pro since they are really good. Other options could be rockford fosgate or Polk audio which I heard are good speakers(for sub and also the others)
I also advise people to stay away from sony xplod head units and speakers because they are of the worst quality I have ever seen. Sony amplifiers however seem to be good although I recommend going for jbl or other good brands.
A good setup with headunit, speakers, amp, sub, plank, box, wiring, power kit would set you back by around 30k or more! so be prepared!