More speaker ?????

[jjjmm56]

I'm starting to assemble my audio system. I got a double din 7" dvd with touch screen. This unit supplys 50x4 watts. When buying speakers is it better to look for a speaker that puts out the most dbs at a wattage closer to what the head unit is suppling. Example a 61/2" speaker will take 200 watts max with a db rateing of 90. A 6" speaker may put out a db of 90 with a max watt of 100. And a 4" speaker puts out 90 db with 80 watts. Which will sound better and is more efficient? I plan to install speakers off to the side of my seats and in the door panels, along with a 1000 watt 2 channel amp bridged powering a 10 pioneer shallow mount sub. Thanks!