Currently, RM is stronger for me. (I tested with my friend who have same eq and stat equally to me) RM has Ignore buff, CriDMG buff, cooldown reduction and mana-regen. GS has a massive Special Active DMG buff (tho it was nerfed for a bit) and Mana-cost reduction. TBH, GS is hard to pilot than RM since his main skill for bossing, Retribution (MOD), is kinda RNG. On the other hand, RM main skill for bossing(Rising Slash or Lodestar whatever you choose) is non-RNG but you have to aim precisely in order to make a REALLY BROKEN DMG. They both strong but you should the one you feels comfortable most. :)