Trellis for pole beans

[beatpoet]

So I'm going to be growing some pole beans this year, first time growing them. It seems from what I'm reading that a trellis is the way to go. I've seen a few different designs out there, but figured I'd see what everyone's experience is with what works best. I'll be growing in a raised bed and will likely be growing Kentucky Wonder pole beans.
I've seen some designs that look like an a-frame with string/twine and some that stand straight up but not sure which is best.