I was going to add Tyree Superman too, but
@jda beat me to it. Most intense blue I've seen, better than OT and HOTO even in my tank. They are more of a dark blue, Superman is more of an intense almost glowing bright blue. Not knocking those other two at all, they are just a different shade.
Definitely agree with SCOP, Homewrecker, and a properly colored WD.
Couple others not mentioned are MattV Pacific Wave and CC Kombucha. They are probably the two slowest growing tenuis I've experienced, and seem similar in skeletal structure and polyp characteristics. They have a nice purplish blue to the tips I havent seen in others, kombucha is almost indigo.
I am a sucker for truly blue corals, and I have to say that the filtered tenuis photos online are such a massive disappointment. Very few of the "high end" tenuis seem to have any actual blue pigment in them when you see them in reality. I dont normally wear orange glasses and most of my tanks dont have any "blue" period.