Personally I enjoy the feel of panniers on the bike. A loaded touring bike handles a little bit more solid to me. Changes are more smooth and no wiggle. Also when im flying down hill I feel more solid. With panniers you can take them off the bike and bring them in the tent with ya, also its a bit more inconvienient to steal 4 panniers as opposed to throwing a trailer in the back of a truck, though its unlikely. Panniers allow for a bit more organization as well, as long as everything goes back where you put it.

Trailers are fantastic with multiple people for larger bulkier items but for a solo person id definitely stick with panniers.