I’ve lived in both places. Jomtien a few years ago, and I’m currently in Wongamat.
Jomtien has more going on, for sure. More restaurants, night markets, etc. Baht buses running up and down Beach Road. Wongamat is less busy. More of a residential area. Nice condos and some hotels mixed in. To be sure, there’s everything you need. Some restaurants, some convenience stores, street food. They keep the beach pretty clean It’s hard to get into too much trouble around here, although a Bolt taxi to central Pattaya doesn’t cost much.