If you are planning on putting money into your car audio system then you don’t want to cut costs on your speakers and speaker system. There is no sense in putting money into everything else and then just using stock speakers. Before deciding which speakers may be best for your needs, there are a few things you want to take into consideration.

Plan your budget and decide how much you are investing in all the other parts and how much you will have left to dedicate to just the speakers. This is the best thing to do first before checking out all your options, so that you spend the appropriate amount in all areas and keep within your car audio budget. Some speaker systems will come with a much higher installation fee and you should take this into consideration before making a final decision.
What you use your car for should be an important factor in your decision. If you engage in long trips and spend hours in your car then you want to have the best system possible, but if you only drive on short trips, then you can choose to get a little bit of a lower end system. You should also consider how long you will be keeping your car for. If you plan on getting a new car or selling your current vehicle, then you might want to keep your budget a bit lower. However if you are making a long term investment then you should raise your budget accordingly and get a system that will supply peak performance for a long time.
The genre of music that you listen to should also play a role in your final system with respect to a speaker system. If you are into loud music with heavy bass then it is important to get a powerful system with an amplifier and subwoofers so that you can enjoy your music the way it was intended. However, if you are more into classical and less intense music you will want to invest in a system that focuses on even distribution and not such an intense sound.