You'd probably notice a better improvement by swapping out your head unit with a nice aftermarket deck (and stock amp bypass).
The stock speakers are alright when driven by a nice aftermarket deck. It's the crappy factory amp with its high distortion and low power output that's the problem, which will still exist with a speaker swap.
But, if you've already swapped out the HU and performed the factory amp bypass or you just want the factory deck, either speaker you suggested would be fine. I'd probably choose the more efficient of the two if you're running them with the stock HU/amp.
