The plastic bed liners don't breath and lets water stay under the liner, more rust. The rubber mat is the most slip resistant. It sits proud of the bed ribs allowing air movement, and can be removed in seconds. Also, it offers the MOST impact resistance.
I take mine out to wash and inspect every time I wash my truck. I have carried motorcycles, stone, concrete construction debris, slept in the bed, dozens of loads of fire wood, and abused the mat more than you an imagine, and it protected the bed so it looks like a new truck, after 20 years, in the northern rust belt (read salt).
1992 PU that has had a rubber mat since it was new....
