I have 3, my husband has one. But that's his and not mine, so I voted 3
My first love: the BeBook Mini. still love that one, despite the lack of a touch screen. It'll be the reader I'll most certainly take with me on holiday and is at all times near me.
I then bought the ProMedia, which has a sipix screen and a horrible battery life. That is is relegated to the kitchen.
Finally, I got the Sony650, which is also an awesome device. But it feels less sturdy than my Mini, so it only sees home use, despite the fact that it has what the Mini really misses: the touch screen... Will I take that one with me on holiday? Probably. So I can show my mother the PRS+ firmware