And to add to the commentary...............

Agreeing with BOBCRMAN, top is best, even better is the fitting with a check valve in it (sometimes called an anti-rollover valve) so that fuel won't spill in a rollover accident. Also, cut the bottom of the drop tube at a bias, it aids in pick up and is less prone to plugging. Hardline on the fuel line is preferred, only a small piece of flexible tubing from the hardline to the tank, and again to the fuel pump (assuming it's mounted to the engine), these two short pieces will compensate for differences in motion of the tank, engine and the frame mounted fuel line. One last note, copper is a catalyst for oxidation of gasoline, in other words it promotes the production of varnish deposits. Yeah, you'll hear lot's of people say they've used it for years and not had a problem, but it's just one more risk not worth taking. Without getting too chemical technical today, the gasolines on the market these days have more unsaturated molecules than in years past, so they're more prone to allowing oxygen (oxidation) to attach, and the copper just accelerates the process. There is plenty of very pliable steel fuel line available that makes routing easier (even sold in rolls).