The best slide to talk about competition of your product or company depends on your specific market.
Most people first try to squeeze all competitors on to some sort of 2x2 matrix. This is a great option if there are 2 distinct axes, or 4 market segments.
You can add nuance by using a 3x3, creating 9 market segments. I prefer to put the competitors locked to the grid, and don't get into debates about where they exactly sit on the spectrum.
But, if you have a hard time finding the definition of these 2 axes, the matrix is probably the wrong format to use. In many cases, the bottom left quadrant stays empty, and/or is meaningless. In these cases, try using a Venn diagram, which is basically a 2x2 matrix with that bottom left box chopped of.
In other cases, a simple bar chart my be sufficient. Rank you versus the competitors with one simple variable.
In most situations, I have to use some sort of feature table that can handle more than 2 dimensions on which to compare the competitors. Choose the comparison criteria wisely, avoid duplication, and give them the same level of abstraction/detail. Re-order columns and rows until you get homogenous blocks if "yes" and "no" cells.
Feel free to be inspired by the example layouts in this post. You can also click on the images, which brings you to the template store where I did the work for you. I frequently update the template store and try to tag slides with relevant keywords. A search for "competition" should bring up all the charts that I think are useful for visualising a competitive differentiation.