Recently, I have come to like rear sights that first, are at my focal length, usually right at or in front of the entry pipe on a longrifle, and secondly, have a square or rectangular notch. I find these easier to hold the front sight level with the rear that way. My front sights are of pure silver, a little over 1/16" thick, rectangular in section looking at the back end of it, with a short 45 deg. bevel on the tip to catch light.
These things depend 100 % on ones own eyes. So what works for me may be a blur to someone else. Experiment.