My groups shrank by over 50% in a couple of rifles I was working on years ago. From that time forward, I have used match primers. For the very small cost per shot, it's worth it to me. Doesn't hurt.
My favorite reg. primer is the CCI BR2. This is one of the mildest standard primers as well. For best performance, you want to use the 'mildest' primer that ensures consistent ignition. Recent tests showed equal muzzle velocity but way lower chamber pressure when these primers were used (compared to other stand primers).
For the magnums, I use Fed 215M. Seems to work in my 7RM and bigger cases. Certainly, if you use ball powders or plan on shooting in cold weather, you need a hotter primer. For extruded, you can get away with less. My next testing after hunting season, is to put CCI BR2 into my 7RM's and see what happens. I hope to reduce operating pressures but retain the same velocity and increase accuracy at LR.
Fed 210M are also very good but show pressure signs sooner then the CCI.
Test one, test them all if you choose. I put an appropriate primer into a load, and work up. I do not switch primers because I am already starting with a great component.
if you decide to switch primers, start loads from the beginning as a change of primer can push your chamber pressures over the top.
By the way, the best (most accurate) standard primer I have used is the Win LR. I still go match but if had to, would go with the Win and be happy.
Jerry