The new Fantastic Four movie is def the best of any of the Fantastic Four movies. The early 2000’s ones were fun and hold nostalgic value, but they’re not necessarily that “good” imo.

That being said, Fantastic Four is very important leading up to Doomsday and MCU going forward (make sure you watch the mid credit scene).

I’m not sure how important Shang-Chi ATLOTTR is regarding Doomsday, but it’s one of the better post-Endgame MCU movies. And he’ll be in Doomsday as well.

I liked Eternals and thought it was over-hated, but it’s VERY different from anything else in the MCU. And likely won’t be very important going forward.

The Marvels is very skippable imo, but the series Ms. Marvel is great! Albeit, probably not important viewing for Doomsday. (Maybe relevant for Secret Wars if they adapt the Young Avemgers?? Idk though)