The order from most realistic to least is the exact same as the way the films were released.
Begins > The Dark Knight > Rises.
I find Begins to be more realistic to be quite odd, atleast the way I remember it, the 'realism' talk only came in when TDK was released.
I just felt Begins was the most explicit in detailing Bruce and how he dealt with that life, keeping it the most grounded in regards to how he trained, learned and evolved into Batman. I felt the sequels just completely lost that feeling in comparison.
Well, we did see Bruce train in Batman Begins - but in my personal opinion, the fantastical Ninja-Illuminati aspect was why it was less grounded. In The Dark Knight, we saw the effect of being Batman had on him by the beginning, and the tone was that of a gritty crime-thriller.
I can see where you're coming from, but truthfully, I find that tone would generally be subjective. Not everyone shares similar viewpoints regarding genre tastes. I really had a fun time with The Dark Knight, and Rises, but I still think Begins is the best of three, and the most realistic for me.