Both hattricks are iconic its own.
I persoanlly prefer Ronaldo one as he did it in over harder context (already 37, every points counts to rescue Man Utd league season, playing with the likes of Rashford, Fred, Matic etc) vs L.Ronaldo (still at good physical age 27, while Real already leading first leg by 3-1 anyway, and he has peak Zidane and Figo behind him).
But quality wise, I think both are absolutely top quality goals, and a clear 10/10 performance. L.Ronaldo one even has opponents fans clapping for him and he was scoring against strong Man Utd team in big European night, so maybe he has the edge too,