reigning supreme

Verb

reign supreme (third-person singular simple present reigns supreme, present participle reigning supreme, simple past and past participle reigned supreme)

1. (idiomatic) To be the most important or most prevalent.
   • During the month prior to writing this article I have made a series of journeys [...]. One was over a main line on which steam still reigns supreme on the principal trains and on which we had a fine run, fully up to the best standards of the locomotive class concerned.1961 July, Cecil J. Allen, “Locomotive Running Past and Present”, in Trains Illustrated, page 401