I'm on my second explorer and I've tried 3 set's of running boards. Everyone has an opinion so there are no easy answers.
My personal opinion is use what works for you. My the kids seem to always step on the threshold of the door when they enter rear doors. (Under 10 crowd) soccer cleats etc) That is my main reason for boards the other is so my wife can access the roof rack. (Me, I step around them
As for style, I hate low riders looks, I hate the high chrome look. I like it to look like part of the vehicle like Range rover, Acura, BMW or Mercedes. For me...the step does not need to be 3 inches off the ground or interfere with the already limited ground clearance. That said, I've tried the Dee Zee (too much body gap) and ATS (too short, too low) and was not all that happy.
Dee Zee +++ Easy, easy to install or remove
ATS Too low to ground, too short (between mud flaps)
EGR ++++ Great looks -- drill
When I bought the EX sport I did not want to destroy the look of the vehicle so I decided to shop again. Almost ready to pull the trigger on EGRs I shopped a few non-standard channels. (save the flames) The EGRs are the best looking in my opinion. Another criteria I had was that I wanted to be able to toss them in a couple years if I did not like and not have holes drilled everywhere. I went with these.
http://www.ebay.com/itm/271844970532?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
I put these on and was very happy with appearance and ground clearance. They fit about 3/4 below the door without drilling.
What I will say to EGR, and many other manufactures, think about the mounts, drilling a little more. Too much gap, too much drilling, no thanks.
For now I'm happy. Wish I could have bought American but nothing in the market for me.