The term "genre" is a fancy way of denoting a type of art. Concerning literature, this would mean a kind of story: drama, action, horror, mystery, romance, fantasy, etc. No two humans are exactly the same, but unlike snowflakes, we do not melt on contact with a solid surface.
They say you should write what you know, but I take it one step further: write what you like. If you don't have experience with the subject matter, your interest will lead you to research it. Or at least you will write with a gusto that is intoxicating to the reader. There are many types of stories that I like to read, and sometimes even the styles I am not familiar with can be inspiring.
It is from the internal wellspring that we pour the words onto a page. There is a delight in the creative process which gives us the energy to carry a tale to completion. Often a great deal of perseverance is required, so it is essential to have a liking for that which you are laboring to make.
The best genre is the one you enjoy most. It is possible to construct a story through much struggle against disinterest. But this creation will likely be tainted by your own malaise. Rather, there is that tale which excites one to write feverishly and end a session in a contented exhaustion.
No genre is superior to another. That is why readers all over the world have enjoyed a variety of styles over hundreds of years. What draws them is the enthusiasm of the author. It is the life's blood of a creative mind... and it is infectious.