With viper - omen - kayo - phoenix - breach the team has a lot more resources than the ascent standard comp (jett - kayo - sova - killjoy - omen). For having more habilities, its more dificulty to play, even because it requires more chemistry and synchrony between the players. On the other hand, the standard comp is simpler and easily balanced, which makes it easy to play.
In other words, both comps played to their maximum potential: VIPER - OMEN - PHOENIX - KAYO - BREACH >>> jett - kayo - sova - killjoy - omen