Nielsen #15 profile is the best as it gives you more room for things like double mats and such and still have room for the spring clips to hold everything in place.
The #11 profile is not deep enough.
#15 is my shop standard and I currently have about 300 ft in stock.
You can get an equivalent profile that is, visually, the same as Nielsen #15 but is cheaper. I think the thicknessof the aluminum is a tiny bit thinner so it is cheaper but works fine.
Where are you located? I could give you idea of where to buy the stuff.
Of course, I could also chop what you need and ship it to you for a good price.
If so, email me and we'll talk.