I would definitely go for a sump. They can be a little noisy and some designs are better than others for that. It's not a horrible sound but it depends what your tollarence for noises is.
Its been a really long time since I set it up so can't remember details but there are ways to make it a lot quieter using valves to reduce flow a little. That then takes away the water falling sound.
A sump will be cheaper, more efficient, give even more water volume and mean you can keep all the equipment out of the display tank.
Edit: a Google for quiet aquarium overflow or weir should give you some useful designs. I mostly used what I think are called twin standpipe designs, the valve was on the main pipe and adjusted so that the water flowing over the weir wasn't dropping as far.