I have a V3 on the 17th right now, but I had a friend who got her V2 to the 50th and the took the battery out and took a break from it. And I also have a V4 on the 7th gen.
I only recently got mine a couple of weeks ago [i think]. But I do pause it alot - as I'm busy with college and stuff. I'm on Generation 2 and the matchmaker has just come, so he has a baby !
My highest is my V3, at generation 21. I don't play with it anymore, and the battery is dead. My V4 is generation 11 currently. And my V1, don't play with it, out of batteries got to generation 8 I think as the highest.