From the ones I have seen overseas I like the ones that seem to allow multiple opening depending on where the handle is.
i.e. flick the handle one way and they 'hinge' from the side, flick it another and they 'hinge from the top.
That said - Hinging them from the bottom so they tilt in at the top seems like a great idea to me - very difficult for someone to climb in the window if its left open. Is that an option for you?