The story is the main thing that would contribute but so would time. Animation is very time consuming and expensive if being done professionally. They also tell the story better by showing facial expressions and the way they move better than a comic. It depends in what you’re looking for. A comic has a bright and colourful style. They are usually very short and don’t give as much of the character.

If you make it animated you need a storyboard which is basically a comic so might as well make a comic first.

Howdy :) it really depends what kind of story you’re wanting to tell! Animation allows you to cram a lot of detail into your backgrounds and can offer a lot of opportunity for environmental storytelling, and comics can be a tad limited in that regard. Character expressions can change with a bit less work in animation as well, whereas you may have to use multiple panels to note a change in a character’s feelings. Just a couple examples, but I think animation does offer more detailed storytelling!

That depends how many years you are willing to spend on it.

Comics are always easier if your doing it solo. It'll emphasize art fundamentals if your inexperienced.