We have a lot of inverted U around here, i feel very confident locking my bikes to them.
Never have used sheffield stands, never seen one, but they look good.
I love art racks, we have one here at the post office of a cyclist and a few more around town.

I don't like waves, too sloppy, and people rarely lock up to them correctly.
Don't like the grid system, well i do and i don't, usually i tend to see junkier bikes in those racks because they find it easier to park into, so they leave the better and proper racks free.

The bike shop i go to has a grid rack outside, but in all reality it is a small area and it works for what it is. But i just wheel my bike right into the shop anyways and lean it on the counter hahaha