I realize this thread is about MIDI drums, but don't overlook acoustic drum loops, which by definition sound "real." I use acoustic drum loops (the ones from Discrete Drums) for 85% of the drum sounds in the three albums posted on my YouTube channel. The Simplicity album is almost all Discrete Drums sample libraries. You might think it would be difficult to find parts that fit what you do, but some of their libraries are multitracked, and what makes them come alive is cutting and pasting. 
 
Real drummers listen to my music and assume there's a real drummer playing. And that's because there is , I just do the arranging.
 
One final tip for MIDI drums: Buy cymbals and overdub them. It can make all the difference in the world, because at least to my ears, they sound more unrealistic than any other drum sounds.

Cakewalk's Groove Quantatise is useful and certainly better than random humanization in most cases because it imparts some sort of feel.

Play around with the parameters and get an idea of how to get results. Remember you can use different parameters on different kit pieces.

There are quite a few preset groove templates but remember you can also use a midi groove on the clipboard.

Not sure if this was mentioned, but another part of realism is the sound of a drum based on where it is hit, so there is sound variation that doesn't translate well when MIDI is firing off a single sample. Velocity alone will not accommodate this, and timing (to me) is the antithesis of a drummer's main purpose. Some VSTis use samples by velocity, and that detail comes through. There are also VSTs that will do similar. However, even with that said...
 
Stepping back into a "bigger picture" for a second. Another big part of drums is how they are set into a mix, and the post-processing done with them. Reverb creates the "room," panning gives placement, etc. I think where "realism" falls apart is when things feel "static" in a mix (or an entire mix is static). Samples are used a lot for drums, and some issues lie with the entire mix and its dynamics far more than a single component. When a mix has "motion" in it from shifting focus throughout, one component (e.g., drums) can be more static than one realizes, yet the piece still be interesting.