Right now I have 10 tension wrenches. I voted my favorite is a wiper blade style with flex twist because this is what I grab first. All of my tools are homemade, so I can't speak for purchased tools.
I have wrenches of the following designs:
1 feather touch made from wiper blade insert.
2 wiper inserts with flex twist.
1 double ended wiper insert without flex twist
1 single ended wiper insert wrench w/o flex twist
1 two prong wrench for double wafer locks made from a steak knife
2 wrenches made from small screwdrivers with plastic ball on end of handle
2 wrenches made from steak knives for the top of various keyways.
The two wrenches made from small screwdrivers are probably among my favorites too. When any other wrench feels wrong, these will almost always do the trick. Also the feather touch works great on most locks.