Betterman

Both are mecha shows that include creepy and horror elements. While having the usual format of secret organization fighting monsters and could be said to have monster of the week episodes, they also take time to explore psychology too. Betterman could be said to be lighter, less crazy Evangelion. 

Similar themes/design/story/animated fights. One goes with the other. 

The weirdest shows. unique atmosphere. magic, tecnology, horror in both of them. 

Both have a "virus" that is threatening humanity, similar action/adventure/sci-fi driven plot that is backed by thought-provoking, Darwinian-type evolution theory. Similar art style. 

The style in each is a lot a like, and the characters in each are very similar.  

Action and destruction are unavoidable with badass main characters that have a pinch of mecha and supernatural phenomenon. 'Bubblegum Crisis Tokyo 2040' shows how girls rock the battlefield without any idea of the real purpose of their fights. 'Betterman' on the other hand is plain smashing and killing with the all powerful male character.  

Both are among the very few anime to be genuinely creepy in a horror sense 

Mecha is pretty common in battle and the killing spree is another. Story-wise, it's pretty even in depth and both the main characters are like weapons being programmed to kill whoever stands in their way. 'Bakuretsu Tenshi' has more modern fighting with advanced technologies, 'Betterman' on the other hand puts its interest on the impossible which is transformation. While watching both series, all you want to see the MCs do is to take down enemies as many as they can and that is the main pleasure of the series.