Yep... all personal preference.
I'm on a Roadmaster and have a 16" Freedom Shield. It's less expensive than a lot of others out there and the "flip bend" doesn't distort the view much at all. I can ride with it up on long cross country rides and get the wind off if that's what I want to do, while looking through the windshield. I can leave it down and look over it and get a little wind in my face too. When it rains and I have a full face helmet on, the windshield is down and the wind hits the visor just about perfectly and clears it of any rain.
I have a buddy that has a 10" or 12" Klock Werkz windshield and he loves it. Fully up, its lower than mine fully down.
To each their own.
Most have a excellent return policy. If you don't take the protective stickers off, install it and ride with it for a while. If you don't like it, you can return it and not have any return fees. If you can find a Klock Werkz retailer, I think they will switch out your windshield and you can take a ride with a loaner to see how you like it before spending any money.