Mazinkaiser SKL

Both are modern adaptations of classic super robot anime, which basically defined the whole genre. Both focus on violent and hot-blooded main characters who fight against powerful foes. Both have a similar feel and plot elements, and were originally created by Go Nagai (although Getter Robo is a collaboration between Go Nagai and Ken Ishikawa). 

Both ovas are by Dynamic Pro and they share the same director. If you just want gore + mecha, look no further. 

Both anime have a similar world setting, violent and bloodthirsty main characters and a lot of violence and gore. They also have cool mecha designs, which reflect the violent nature of these anime. 

While there is no Mecha in Garo: Vanishing Line, they do share some similarities. In these two anime, you have a violent badass main character that fights against evil powerful beings. They have a similar manly tone to them as they both have heavy metal music, plenty of nice action scenes and lots of violence/blood. You can get testosterone fueled rampage of enjoyment in both of these two anime.  

Absurd fast paced and over the top mecha battles with dynamic action and awesome designs. Characters with a similar "who the hell do you think I am" attitude.  

Two heavy-packed action anime about nations who fight for domination of a limited space (Machine Island in SKL and Lingalind in BA) using magical giant robots until an overpowered protagonist with a cooler robot suddenly appears. Mazinkaiser SKL is basically a much more dynamic version of Back Arrow with awesome animation and hand-drawn robots. 

Both anime have a similar world setting, violent and bloodthirsty main characters and a lot of violence and gore. They also have pretty good mecha designs. 

Both are mecha anime featuring hot-blooded and violent main characters. While they lack something in terms of plot, they make up for it in intense action and epic fights, creating a similar atmosphere of adrenaline and testosterone. 

Like Shin Mazinger and Mazinkaiser, this is another continuity reboot with more original material, featuring two new characters.  

the MC looks the same plus a few other traits but Kenzen Robo Daimidaler is Ecchi, Mazinkaiser SKL bloody 

Just as GGG Final is the 'more adult' version of GaoGaiGar, SKL is is a more no-holds barred take on the Mazinkaiser concept. If you loved Final for it's epic battles, high production values, noticable but not intrusive fanservice and excellent robot design, SKL just might scratch a similar itch. 

Modern remakes of old shounen franchises, these anime feature manly protagonists in postapocalyptic setting and great looking fights.