I personally think Mega Charizard Y has better synergy with other sun abusers.
I think you'd have to be mad to disagree with that. Zard-Y is definitely going to be the go to for sun in OU. When I said higher tiers, I just meant higher than PU where Torkoal sat through Gen 6. I don't remember the weather rules for lower tiers, but if weather is legal I can certainly see it rising higher.