Assuming that the attention received by the debut or comeback is equivalent to the attention it actually received which comeback should have been a debut instead.
Nct U: Boss as debut, 7th sense was too artistic for kpop stans to understand I fear, and especially as the very first song to mark the debut of sm nbg, I think it didn’t fulfil what a debut should have , which is to immediately attract a lot of attention, so boss which is very easy to listen, Hugh energy release would have served better as their debut. Also if 7th sense was released later when they had more attention, I think I would have consolidate their fanbase, feel like 2016 stans didn’t appreciate experimental music as much. But now it’s all the rage.