All of them suck. I prefer my custom contours which can go to even 1 ft if needed, but they're a bit intensive to set up.I'd like OnX a lot more if the contour interval wasn't so wide. I think it's 40'? That's all well and good in really hilly areas, but where I hunt, it's mostly flat with more subtle variation. 10' contour intervals (like the USGS quads) give me a much more accurate representation of the land.
This is something I really wish they'd make configurable. They may not have the raw geo data to do it, though: I don't know.