I prefer the Meprolites for one reason: due to the fact that the tridium tubes are cased in plastic WHITE sleeves, during the day, the Meprolites will appear to have a bigger dot than the Trijicons as they utilize a silver tube, which gives a smaller dot appearance.
If you see 2 guns side by side, one with Meps and one with Trij's, you'll see a big difference in aparent dot size and therefore visibility.
CMOS