I like both just fine for different reasons, but Wildwood is tiny. You can walk from the very end of the boardwallk, down all the blocks of Wildwood, and then through Wildwood Crest, all the way to the end, in less than an hour, no problem. It has a very small town feel and we felt like it was very limited in restaurant options, and there isn't much to do outside of the rides on the boardwalk. All of the motels are VERY old, so no high rises.
Ocean City is hundreds of blocks, much more real estate, things to do, restaurants, golf, candy shops, etc. Plus Bethany and Rehoboth are like an extension of OC. If you are staying in one for a week, it's easy to go to the others. They EACH have their own boardwalk. Rehoboth is a pretty small beach and boardwalk area compared to OC, MD, and I still think it alone is bigger than Wildwood, NJ. Rehoboth has great rides as well.
I have been to both every year for the last 4 years and I'm not sure what people are seeing in Wildwood that is "more to do" than Ocean City. I feel like it is infinitely smaller!