Bethany Beach residence inn is fantastic. Have stayed twice since they opened. Beaches crowded in season...water and beach exceptionally clean. New boardwalk (only 4/10th of a mile long) Rooms new and clean plus RI full kitchen.
I would recommend off season for price and a less crowded beach. Hotel restaurant is nice too, especially happy hour with fresh squeezed juice and oysters shucked in front of you.
Choosing between these two hotels is easy. The Bethany Beach Ocean Suites Residence Inn sounds head and shoulders above any CY I have stayed at in the USA.
However, Bethany is so different from OC that someone who likes OC might be bored to tears in BB and someone who wants a quiet place with a nice beach and some good restaurants nearby would certainly prefer BB over OC.
Ocean City has a long and busy boardwalk with all sorts of action, including typical beach fare, water slides, bars, amusements, etc. Some love it and some think of it as busy with junk!
Bethany is quite the opposite! So choose carefully, depending on your personality rather than what other people think is better!