It depends what you want to do with the property. Will you use it as a second home? or are you planning to rent it out?
The better buy will depend on where a property is listed vs the value and how much you can get for. The small cottage might have a more motivated seller than the beachfront condo.
The better investment (if you are planning on renting it out) might be the oceanfront condo. If you are planning on renting a condo, you need to know what the minimum allowable rental term is. Some associations will not allow you to rent for less than a year. However, most beach properties will bring as much in a summer rental as they will for the year, and you get the money upfront.
The way to figure it out is to look at what the mortgage, taxes, and HOA dues (for a condo) will cost you and then what rental income you can expect.
In my opinion, a rental beach block will bring in more income than a small bay cottage/house. If you can find one in Avon, that town gets higher rent than Bradley or Belmar.
I am the rental manager in my office and I am a landlord, too. If you have any other questions, feel free to reach out to me via Trulia or my website.