Honestly any of the 6/7H is pretty face roll and doable I would personally start off with what you guys are best at in normal modes. I will use my guild as an example, pre-nerfs we killed Alysrazor 2nd on Heroic because we absolutely shit on it on normal mode. We now kill it 1 healing before the vun phase even ends and have 3 people flying.
Rhyo can easily be "muscled" down with the nerfs but if it just isn't working out, move onto something else to find the guilds strengths to build up that momentum.
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