I know this is an old post but I was considering upgrading the speakers too in my 2017 Versa Note. There are plenty of good speakers well below $100 a pair. When using a stock radio there is the issue of diminishing returns for speakers over a certain wattage.
A few tips for choosing the best speakers:
If you are sticking with the stock stereo, choose a speaker that has a high sensitivity (dB) rating. 90dB and higher should be fine. Consider speakers with a 90-93dB rating as this will allow you to get the most volume with a low wattage stock radio.
Sensitivity is more important than RMS wattage since most if not all speakers will be able to handle the low wattage that the stock stereo will deliver with no issue. Higher wattage will not = louder sound.
Maximum RMS power, or peak power, means almost nothing when using a stock radio. Unless you are going to be using a seperate amp, do not focus on maximum power. The stock radio will clip the signal long before the speaker's maximum power is reached.
You might be able to use a lower impedance speaker. Some of the performance ones are 2-3 ohms, but this will put a heavier load on the stereo and will increase distortion.
With this in mind I was also considering the Rockford Fosgate R1675X2 or the Kenwood KFC-1666S or Kicker 43CSC674 speakers since they have a ~90 dB sensitivity rating, although the Rockford is the only one that is backed by CEA-2031 industry standards (which means you can trust the power ratings). For around $35 a pair I see no reason to spend any more than that when using the stock radio. The only thing that would improve the sound by much more is by using a component speaker system with a passive crossover, and surface mounting the tweeter.
EDIT: right after I made this reply I purchased those Rockford speakers since they were on sale and Crutchfield supplies the wiring harness and speaker mounting bracket for free. These speakers have over 2,000 reviews on Amazon.https://www.crutchfield.com/p_575R16...e-R1675X2.html