I recommend the fuel dot.

The valve can get a small piece of dust or grit in the valve and the engine will idle OK, but when at full power it will suck a little air and drive you crazy trying to find out what it is. I had a Quadra do this one time after I had been using as valve for some time. I was getting to send it in for service when I decided to try routing the fuel line around the valve. Worked great.

If you want to use a valve anyway, plug up the end that goes to the engine and run the tank end to a third line the same way you would a fuel dot. The valve in the middle is just looking for trouble.