All the rigs at work used a round connector plug so that is what I used when I wired my trailer. Even with my low usage, I've had to replace it once already due to corrosion . Again, it is getting difficult to get a good connection. Once I get it jiggled around so it works, it seems to stay put, as I drive with my lights on and never see my marker lights flicker. There is also a flat plug receptacle next to the round one. I was wondering if they might be a better connection...as in less slop. What kind of connection do you guys use/prefer?