Originally Posted by
unijabnx2000 #2 is essentially like stock and how mine is now,
but I was watching a mighty car mod video a while back and they briefly said they use #1 because you wont heat up your fuel by allowing it to cycle into the engine bay and then back to your tank. I think it the turbo V8 Stagea build video. Thats also how they did the fuel system on Super Gramps.
It is probably going to really depend on your specific application. In most cases, #2 will be what you want. Pressure is the same across the rail, the regulator will adjust for pressure depending on how much the injectors are flowing, etc. #1 will not allow for changes in fuel usage (pressure drop), and will only try to regulate pressure supplied by the fuel pump. #1 may require an adjustable regulator in order to have a bit more pressure going to the rail than a stock config.