I like against the grain for the look it can create with stripes, gingham or plaids. But then I like the old/antique look of the quilts made from whatever remained of old clothing, etc.
When I finished a quilt my grandmother had pieced, I found the bias-cut 10" squares were a real problem with stretching and I had to redo the border a few times to get the quilt to lie flat. Still, the finished quilt turned out well.
If you are piecing shapes other than squares, there will inevitably bias pieces...you just have to watch your stitching.
So I suggest, go for whatever you like.