Way back when we used to use level lines. These were fine for fishing smaller waters & in tight quarters, but if you needed to get further out, forget it. They were difficult to get a lot of distance, at least it wasn't easy. I'm not even sure where you can get a level line these days.
Double taper lines are better for delicate presentations & - in my opinion - all around general fly fishing. The line loops & unfolds in the air in the typical way. You can cast close in & further out with these lines, no problem. They're also good lines for roll casting, too.
Weight forward lines are better for distance, driving a fly against the wind, & throwing larger flies. They limit the delicacy of your presentation some, but a very good caster can overcome that. If you need to shoot some line, weight forward is what you want.
Below is a short video of Tim Rajeff talking about fly line tapers. He does a great job of describing these in simple, clear terms - & yes, Tim - an indicator is a bobber.
So it doesn't matter if your rod is made of bamboo, graphite, or fiberglass the line you need will be determined by how you'll fish it.