Personally I have fun when I clear rifts quickly. There's something about seeing every monster on the screen just instantly die .
Ill be honest, I'm bored of t6 rifts. They're too easy right now. It doesn't take much to demolish t6. It's even worse in a four man rift where everyone is fighting over the same one shot. I do still enjoy running grifts and really wish that there were a t7 and t8.