It still does more damage than the other GLD WS's, and when you BR for a 2x damage buff you can see it shine. I've had 300-600 Riot Blades on the NM's quite often in BRs and it can actually hit the mobs right arm from the front which makes it for easy Scimitar incaps.

Though, as stated, the best WS's to use are Phalanx and Luminous Spire for NM's if you are not joining BR's. Phalanx has no stamina cost, and Luminous Spire never misses and gives the mob Mdef. down.

For doing random leve's or farming... it honestly doesn't matter though I just use Riot Blade to see silly numbers.