I've been using Boston Acoustics 5.25 pro's. They sound incredible and can take a crapload of power.
That said, there are dirrerent price points or categories that speakers fall into. Low, mid or high end. Take the mid range price point for example. All the speakers that fall into that category have to compete with all the other speakers in that category. For that reason they will all be fairly close in quality.
Things to keep in mind are fitment, intended use (amp power or deck power), speaker sensitivity, crossovers, seperates or coaxial, and of course how they sound in the car.
Just a suggestion, but no matter what brand of speaker you end up using, it's a good idea to get a small amount of dynamat and wrap it around the outside of the pod to reduce vibration. Also a little fiberfill or fiberglass insulation inside the pod will usually help with bass response.
Listen to the same music on different types of speakers. Choose one and install it in the car. Make sure you can return them if you don't like them. Remember, everyone's ears are different. Stay with a good brand that sounds good to you.
Good luck !