If you want a good brand for bass, I recommend Kicker. I have all 6x9" Kicker door speakers and not only do they sound amazingly clear, but they produce good bass for door speakers. Some even come with tweeters which focus on higher frequencies for added clarity. The only problem is they can be somewhat expensive. You didn't specify a budget though so I have nothing to go off of.
As for being afraid of "looking nice" causing breakins. Most door speakers are completely covered unless modified so you won;t have to worry about how they look.
How much exactly are you looking to spend? Car speakers come in packs of two so you would be paying for 2 front speakers, and paying for 2 rear speakers. Also, what size speakers do you need? If you don't know the sizes post the exact year, make, and model of the car and I will just look it up via crutchfield.
Once you post the budget and size I can post suggestions better suited for you.