Fate/stay night: Unlimited Blade Works, Beatless Recommendations
First of all they both have a similar plot in that both are centered around servival of the best.
They both revolve around the characters reciving aid from an ally that is more powerful then themselves.(fate zero is reserected magical super spirit people while beatless is androids with hyber andvanced ai and abilities)
they both have a very interesting cast that all have their own objectives and desires out of these events.
finally they both have many different interesting and changing relations between each character (for fate both spirits and humans, for beatless both android and human)