I liked the approach and design on ego ... the thought there is a dude in space who has the same mind of a literal living planet and can control it is INSANE , at least in my view
He had a very entertaining personality and was badass enough to buy him as the BBEG of the entire MCU up until that point, but I feel he has lost some of his charm due to being so popular, and people who unironically think he had a point are genuine morons.
Marvel villains just look cool and get one role in one mediocre movie most of the time literally none of them are complex characters besides maybe Loki and Ultron.