Your question has no answer. Everyone who replies is going to say it's the speakers they have. It's like taking a poll of who has the best mother...everyone is going to vote for their own.
Bottom line is ANY aftermarket speakers are going to be WORLDS better than your factory ones, even when they where new. Add ~20 years... you get the picture.
Following the good/better/best categorizing:
If you're staying with stock head unit and wiring, then you're wasting you're money buying anything 'best', and most things 'better'
Now I'm not saying just go to your local flea market and buy the first set that you see in the correct size, but probably anything on the shelf at Walmart will suit those needs.
Tip: cross reference what's on Walmart shelf to Amazon
Crutchfield is an excellent source of information as well.
You could spend weeks or even months researching this and still be unsure, or you can just go buy any decent set today and will be happy.
Now without further adieu... The best speakers are without a doubt Alpine SPR series, component editions up front, and coaxials in rears. Kicker makes the best amps, hands down. Get a kicker SX700.4 to push them Alpine SPR's, and bring it all home with a JL15W7 pushed by a RF10001bd
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