best method of cleaning this up?
I've run into this frequently over the years and I'm just finally getting around to asking.
I'm working on cleaning up an image which was resized from a smaller image. Here's part of it.

As you can see, there are curved lines and straight parallel lines.
To clean it up I've tried a number of things over the years... select color range, pen tool, curvature tool, and other such things. I've tried painting selections as well. I've probably done it a dozen different ways but I can't escape the feeling that I'm putting far more effort into it than I need to be.
So I thought I would ask here... what's the easiest method to clean this up so that it has nice, clean lines?