I've tried all the usual types, clamp on, magnetic, various 'sticks'. The best one I found was the "quick stix" available at Bailey's but the plastic rods are so fragile they will break if setting them down. A replaciment is a 5/16" still rod theaded 8x1mm. Quick on, quick off.
I have reverted to hand held measuring stick - bestof those I discoverd was in the plumbing section, white plastic "riser" rubing for plumbing fixtures. Just the right size to hold, white stands out when you set it down or drop it.
Worst method I tried was floppign the saw back and forth 90" twice per cut...well, that and "calibated eyeball".
Always wonder how the "Mingo" works out. I suspect most of them are tried out a few times and then become shop queens.
Harry K