Both are adaptations of action manga from the same creator, Atsushi Ohkubo.
Both have outstanding animation on a consistent level.
Both have incredibly imaginative settings, top tier character designs and great art direction.
Both lost important people, blamed him for being different. They hate being seen as a demon, but they seek the truth and protect people. Two series about a group that fights against supernatural beings with their own origins. In short, a good mix of constant action, comedy and ships.
Both super powered shonen anime with main characters who are both desperate to become "heroes". Both have supernatural aspects. Both series are very lighthearted in general with good comedy however can also ramp things up when they get serious/dark. Both have excellent OST's and character designs.
Both are adaptations of battle shounen manga with excellent art, filled with action scenes.
Both have main characters that desire to become heroes, but in different ways.
Both are about saving people, rescuing those in need and in despair.
Both have memorable and lovable characters.
Both of them have excellent character designs in general.
Both of them have really cool looking and memorable villains.
They aren't the most similar anime, but they have some similarities.
I can't help but remember Boku no Hero Academia as the MC of Enen no Shouboutai constantly repeats his desire to become a hero.
Also, they are both packed with action and some sort of superpower!
Both shows follow organisations that upkeep public safety from a unknown threat (Scouts & Titans + Fire Force & Infernals respectively). Both main characters also have tragic back stories of loss of family members to this unknown threat which motivates them to join these organisations which are essentially on the front lines combating the issue. They both also have great OST's and art styles.
Both are intense action packed stories about groups of brave people that fight against monsters that are a threat to humanity.
Both have a central mystery regarding the origins of the monsters that terrorize humans.
Both have darker themes and elements of horror.
Both have unique settings.
Both action heavy super powered shonen shows with main characters who are stigmatised for events in their past that were completely out of their control. Both also seamlessly switch between lighthearted humour and serious/dark scenes
-Both MCs are trying to become a significant figure in their setting (Hero, Hokage)
-Both worlds are unique and creative
-Characters have some kind of powers
-Both series have martial art based fight scenes
-Both MCs are disliked for something they can't control
Both Anime have:
-Protagonist who have lost family in supernatural ways
-Protagonist join forces that attack said supernatural being
-Protagonist has a goal to find cause of supernatural phenomena
Both have high quality animation especially with fast motion scenes.
Both are anime about a team fire fighters fighting fires and strange fire creatures. Both came out in 2019.
Atsushi Ohkubo (Creator of fire force ) even said his idea was stolen from the staff of Promare.
Both have a sentimental sacrifice necessary connected with "monsters" that was go "people" ,though Plastic memories be an "sci-fi romance" with a story board different and Enen no Shouboutai an shounen.
-Both MCs are on their journey to become someone important (Hero and Hokage)
-Special powers with different categories
-Both MCs seek recognition from others
-Both MCs suffered loss at an early age
-Both series got some cool openings
Both are about special teams of people with supernatural powers that fight against monsters.
Both take place in eccentric and beautifully detailed urban settings, where everything is brimming with life.
Both are action packed and have fantastic animation.
Both have sets of memorable and lovable characters.
Both have brilliant character designs.
Both shows follow/contain organisations that try to maintain public safety (The Fire Force and Hunter Organisation respectively) and have supernatural aspects and unique & interesting art styles. They also both have great OST's & humour.
Both Dr. Stone & Fire Force have amazing OST's and character designs. Both require the same time investment and are high intensity Shonen shows with intriguing plots. These series also complement each other being watched together weekly as they have different strengths but enough similarities that fans of one will likely also enjoy the other. The change of pace between these shows can be refreshing while they still appeal to the same target demographic.
Both are action packed battle shounen fantasy stories where the main characters have special powers.
Both have main characters that are driven to solve some dark mysteries about their pasts.
Both take some inspiration from steampunk.
Both are filled with lovable and memorable characters.
Both have awesome fights and great action animation.
Both have young main characters that have incredible powers.
Both have older and more experienced characters that guide the younger protagonists on the right path, encouraging them to use their powers to help other people in need.