I personally use the Blaze cummerbund with with cobra buckles. I switched out the standard velcro one just shy of two years ago. The buckles seemed to take a couple months to break in, but now they are smooth on and off without any issues on my chosen side (right). I ended up sewing the front flap of my carrier over the velcro portion to ensure it never comes undone. The side velcro flaps were folded backwards and sewn into their own pockets, allowing me full access to the molle webbing on the sides for attachment points for the buckles. This has been a hit on the department with everyone asking me how I did it.
TBH, I think it's a user preference matter. My partner liked my setup so much he went with the cobra buckles, whereas my old partner preferred the first spear tubes and went that route. So far I would say it's about 2 to 1 on the buckles to the tubes, with no issues from anyone on the watch. IMO you can't go wrong with either.