If realism is really a concern for you, 3D animations will work the best. We live in a 3D world after all. Note that you can have 3D modelling & animation, but keep the gameplay in 2D. For instance, check Trials: https://youtu.be/mhsusQvTab8?t=2m23s.
On the other hand 2D animation can look great if done properly, even if it's not realistic. Check Rayman Origins for instance: https://www.youtube.com/watch?v=syNWMkBSmLU. It's also simpler to implement & author.
But since you're a beginner, I suggest you start small and prototype some basic gameplay without even thinking about animation. You'll see how this goes: animation is tightly coupled with gameplay, so it's probably something to figure out after you have a first playable prototype.