This may be a wild opinion that no one agrees with, but I feel like the Inart Gandalf reminds me more of his appearance in The Hobbit, with the more aged look, fuller face, more steel grey (rather than brownish grey) hair, and frizzier beard texture. Inart is undoubtedly the more realistic portrait, but when I actually look at screenshots and promotional shots of Gandalf from Fellowship, I do see more of a resemblance in the Asmus portrait. I've attached photos of FOTR Gandalf and The Hobbit Gandalf for comparison.
I think just a bit more effort would have pushed the Asmus Gandalf to the next level. Mainly the bushy eyebrows, which were present in the prototype for the upgraded head, but absent from the production heads. Maybe also a bit more reddish paint around the eyes for added realism. As for the hair, a bit more variance in colours (same can be said for Inart), more styling apart from the (well done) hairline area, and styling the moustache (hard to explain, but FOTR Gandalf has a distinct, wavy moustache that is raised from the rest of the beard, whereas The Hobbit Gandalf has a frizzy moustache completely integrated with a frizzy beard).