There is no 'best' speaker. It is directly related to your tastes. What types of music do you listen to?
I'm partial to SEAS Lotus, but that might be more than you're willing to spend (
www.mobilesq.com).
I've used Arc Audio's KAR 6.5" comp set, and for a budget comp set, it blew me away. Flexible crossover, STRONG midbass in a sealed kickpanel, and tight and clean tweeters.
How did you rewire your setup. What speakers are you using? What time of headunit? Amplifier? IF you're using an amplifier, do you have the rcas run down the same side of the car as your power wire? Size of the power wire?
I'll see if I can help.