The first one, well, the anime is ok, but the novel is better.
The second one... steins gate 0... the VN is years better than that anime.... that anime make me sick.
not only "some" things, about steins gate, they cut some explanations about the machine and other things that make the story special. But in general, the anime was a good if you compare with the VN.
But if we talk about steins gate 0... jesus, no. that thing should be in the hell. They cut the story, cut explanation, destroy the context of the best scenes from the VN and make them like "oh, so that is was happen? nice!" "oh look that"...
To be clear, i played the VN, both of them.
Steins gate is good, you can play the game or take the anime, both choices is ok, but if you want more context and explanation, go for the game.
Steins gate 0 is a masterpiece (better than steins gate in my opinion) and im really sure when im saying that the anime is a big shit. Cut story, cut the context, cut scenes, take the routes of the game and put them like a lineal puzzle without context and destroy the best scenes of the game, scenes that make you say "oh jesus WTF" "epic moment" if you see them in the game, but in the anime is like... "oh ok"
(Speaking about one of that scenes, and trying to avoid spoilers, that scene is called "re-awake" and is divided in 2 parts in the game. Well, they only animated one part of that scene and even when they do that, they change the characters in the scene and destroy the epic moment. And the other part of the scene... well, they just delete that part, who in my opinion, is the best part of the game)