I NEVER pieced my borders with diagonal seams. That sound like something the quilt police would say. Most quilts I made were for competition, For queen size quilts, I always bought the length of the quilt and that would be enough for the borders and the binding.

Once you quilt it, the border seams won't really be as noticeable anyway. I always use straight seems if I need extra length to a border.

But what "looks better" is in the eye of the beholder! So that's the opinion of the author, but I don't necessarily share it.

As a quilter, if I saw a diagonal seam on a border it would probably draw my eye, because I would be wondering why the quilter went to the extra effort to put a diagonal seam there!

I always heard that if the border was over 3" not to sew it on the diagonal anything less than that is fine.

Straight seams are fine. Depending upon how you quilt it it , the straight seams vs. mitre corners won't even be noticed.

i use straight seams all of the time... but none of my quilts are show quilts LOL

I do straight all the time, it's okay!

I do straight seams. I like them better!

I do straight seams all the time as well...not only one or two seems, but sometimes dozens of straight seems when I make a pieced border.

I make straight seams on a wider border. Diaginal seems take up too much facric. on thinner inner borders I will make diaginal seams- Why???? not sure! After you get the quilt done you will not be able to tell if the seam is straight or diaginal. also I do ot match patterns/prints unless it is a stripe