You did not say Saltwater, Freshwater or both.
Having had a few boats (Saltwater) for over 30 years including a 33 foot boat I would vote for Magma.
What I like about Magma is that parts are still made for my 30 year old model. They cook well come in round or rectangle. & have many options.
You can also buy them as charcoal or gas or electric.
https://www.westmarine.com/grillsI think know some modes have the ability to cook from a griddle too or use them as a stove top (options).
They have legs or little stands for table mount so that you can use them on a beach or at home if you want .
I bought the round one (gas) as it was all that was out 30 years ago.
They also have so many choices for mounting the grill on boats.
The only downside is $$$$ now if you are talking freshwater you can save money by buying another grill for a lot less.
These really hold up well in the salt ocean.