Worth repeating: It depends on the story.
If you want a story with lots of thinking and character growth... It's still not one or the other.
It would be interesting to have an extravert who usually just blows through life stop and suddenly consider their actions, the people they hang out with, and how they can be better.
It would be
easy for an introvert to spend time thinking, since that's natural for someone who doesn't like company. Their growth might be them deciding to push forward in interactions with a particular person(making it great for romance).
If you want a story about companions moving forward with their friends to achieve Objective... There's room for either.
It would be
easy for an extravert to gather a following, collecting a party of individuals perfectly suited to the challenge. They could win over enemies, mold the political landscape, and make you laugh while doing it.
It would be interesting to have an introvert who can barely get a word in forced to gather an elite party... Just to fail miserably. Instead, they have a group of volunteers who are there for personal reasons, and then the MC has to slowly open up to them, turn them into the people
capable of succeeding.
So, you can choose between easy and interesting. Naturally, it's better to go with easy unless you want this to be one of the main hurdles the MC has to get over.
No such thing as an introvert, anyone who says that they are one was just improperly socialized as a child.
With that out of the way, extroverts are a lot more interesting to write. They act, they're not acted upon. It makes things more dynamic.
I tried so hard, but I just can't let this go. My response:
"There's no such thing as Americans, just Brits who don't have enough respect for the Queen."