Just went to Wildwood this past weekend for the Band/Guard championships, so I realize it was off season and hard to compare. I've been to OCMD many times, including in the off season, but that was my first time at Wildwood. Both are great for the beach, but it seems to me like there is so much more in OCMD. We had heard the recommendations to stay in Wildwood Crest over Wildwood as well, and while we did, it was still walking distance to the boardwalk- I'm not even sure why they are considered different towns. Ocean City is MUCH larger than the two combined- many more streets, restaurants, stores, bars, etc. Plus, we usually stay in Rehoboth or Bethany in DE to enjoy being away from all the crowds, but can still drive down to OC for fun. Wildwood has Cape May, but there still isn't a ton to do besides hang on the beach.
Morey's Piers in Wildwood is way better than the inlet rides at OCMD. And I say this even though I went on the off season. We still got to ride quite a bit of the dry rides, and although the water parks were closed, you can tell they have quite a bit. Ocean City, MD does have several other waterparks though- they just aren't on the boardwalk. And again, there's Rehoboth which also has rides.
We had a really hard time deciding where to stay. Almost everything in Wildwood is 1-2 star motels!

We ended up enjoying where we stayed- the Royal Hawaiian- which is right on the beach in the Crest. But again- I'm not sure that too much has been built in this place in 50 years- very different than the high rises and condos all down Coastal Highway in OCMD. It's a very charming small old beach town- we found all the "sun decks" above the pools amusing. Pretty much every place has efficiencies as well- which is a good thing because there aren't too many options for food off the boardwalk. Huge contrast to OCMD.
I don't think you can go wrong with either one, especially for a short stay. I enjoyed Wildwood, I just consider it a beach experience on a much smaller scale than what I'm used to with the OCMD/DE beaches.
And another unrelated tidbit- I used to LOVE those babboons at Six Flags. Sure they ripped the rain guards off of our windows, but dh and the kids and I never laughed so hard in our lives- I'm sad that they've changed it!