Others have given a lot of good suggestions. As I've mentioned before, Fate/Zero is a good fantasy anime. And Sword Art Online is technically Sci-Fi. Have you seen the Gun Gale Online spinoff? I thought that was fun.

But for a series about sci-fi and fantasy crossing over, the "to aru" series must be mentioned.

The main setting is a city of science. They have technology ahead of the rest of the world and many of their people have developed "esper powers". Outside the city are various factions that rely on magic instead.

A Certain Magical Index (Toaru Majutsu no Index): The main branch of the series. First 2 seasons are good. Season 3 has a dramatic drop in quality of writing because they tried to adapt too many books into that season.

A Certain Scientific Railgun (Toaru Kagaku no Railgun): A spinoff that runs parallel to the main branch. Two seasons. Three seasons.

A Certain Scientific Accelerator (Toaru Kagaku no Accelerator): A side story.

Alternate between watching Index and Railgun since they're concurrent. The timing is a bit off, but figuring out how they fit together is half the fun.

Accelerator is the last anime from this series that was released and should probably not be watched until after watching the first two seasons of Index/Railgun.

There also a movie, A Certain Magical Index the Movie: The Miracle of Endymion (Toaru Majutsu no Index Movie: Endymion no Kiseki). It's basically another side story that should be saved for after getting familar with Index/Railgun first.

Others have given a lot of good suggestions. As I've mentioned before, Fate/Zero is a good fantasy anime. And Sword Art Online is technically Sci-Fi. Have you seen the Gun Gale Online spinoff? I thought that was fun.

But for a series about sci-fi and fantasy crossing over, the "to aru" series must be mentioned.

The main setting is a city of science. They have technology ahead of the rest of the world and many of their people have developed "esper powers". Outside the city are various factions that rely on magic instead.

A Certain Magical Index (Toaru Majutsu no Index): The main branch of the series. First 2 seasons are good. Season 3 has a dramatic drop in quality of writing because they tried to adapt too many books into that season.

A Certain Scientific Railgun (Toaru Kagaku no Railgun): A spinoff that runs parallel to the main branch. Two seasons. Three seasons.

A Certain Scientific Accelerator (Toaru Kagaku no Accelerator): A side story.

Alternate between watching Index and Railgun since they're concurrent. The timing is a bit off, but figuring out how they fit together is half the fun.

Accelerator is the last anime from this series that was released and should probably not be watched until after watching the first two seasons of Index/Railgun.

There also a movie, A Certain Magical Index the Movie: The Miracle of Endymion (Toaru Majutsu no Index Movie: Endymion no Kiseki). It's basically another side story that should be saved for after getting familar with Index/Railgun first.

Others have given a lot of good suggestions. As I've mentioned before, Fate/Zero is a good fantasy anime. And Sword Art Online is technically Sci-Fi. Have you seen the Gun Gale Online spinoff? I thought that was fun.

But for a series about sci-fi and fantasy crossing over, the "to aru" series must be mentioned.

The main setting is a city of science. They have technology ahead of the rest of the world and many of their people have developed "esper powers". Outside the city are various factions that rely on magic instead.

A Certain Magical Index (Toaru Majutsu no Index): The main branch of the series. First 2 seasons are good. Season 3 has a dramatic drop in quality of writing because they tried to adapt too many books into that season.

A Certain Scientific Railgun (Toaru Kagaku no Railgun): A spinoff that runs parallel to the main branch. Two seasons.

A Certain Scientific Accelerator (Toaru Kagaku no Accelerator): A side story.

Alternate between watching Index and Railgun since they're concurrent. The timing is a bit off, but figuring out how they fit together is half the fun.

Accelerator is the last anime from this series that was released and should probably not be watched until after watching the first two seasons of Index/Railgun.

There also a movie, A Certain Magical Index the Movie: The Miracle of Endymion (Toaru Majutsu no Index Movie: Endymion no Kiseki). It's basically another side story that should be saved for after getting familar with Index/Railgun first.