[Guyver Spawn]

For superhero anime, I suggest these:

8 Man (The first cyborg theme superhero in anime and manga. If the original 1960's TV series is too dated for you, check out 8 Man After which is a OVA series from the 1990's)

Android Kikaider (I found the anime adaption to be pretty underrated. I think it's worth watching even if you never seen the live action show)

Casshern (There is three anime versions of this character. One from the 1970's, 1990's and recently from several years ago. It can go either way on what version you want to watch)

Concrete Revolutio (A pretty recent anime series and it's a lot of fun too)

Devilman (A very dark and violent series. If you want something dark and violent, watch the OVA's and read the manga. The 1970's series is much more tamer and feels pretty similar to Ultraman at times)

Guyver: The Bioboosted Armor (A bit different than your normal superhero anime and manga, but it's still good. The series seem to be inspired by some themes from Kamen Rider)

Skull Man (Based on a manga from Shotaro Ishinomori and would later inspire Kamen Rider)

Tekkaman Blade or the original Tekkaman: The Space Knight

Zetman (Another more darker theme superhero series)