I usually prefer a heavy bend on longer wands (60"+) and shorter bend if any on short wands (48"). I dont like the pressure wearing me down, if the bend is just right, it supports its own weight a little better.
I prefer straight wands, unless I am in a tight area, then I want a little bend. My experience is that bent wands wear on me more than the straight wands do.
I wonder how many, like myself, have used whatever came with their first rig. I was wondering if the bend was good for something on flat work. I had ten years cleaning never used anything but straight, someone handed me their gun and turned on their machine - that thing flew up in the air like a rocket! I can't imagine fighting that thing while working.
I used strait wands for a few years then tried a bent wand. Now all I use is bent. It's hard to get the right angle on a truck with a strait wand. And once your used to working with a bent wand you learn to make that bend work for you not against you.