IMO all the actors in LOTR were quite good except Frodo, Elrond and Eowyn. The miscasting of Frodo was a huge and damaging mistake. Much too pretty for a hobbit, besides his absence of acting ability.
Gandalf in particular was excellent. He was almost exactly as I’d envisioned in my head for 40 years.
The actor who played Gandalf was who I wanted for Dumbledore in Harry potter movies.