I've seen Android running on Raspberry Pi 2 on Youtube however I have not seen Android running on the B+ device.
What version of Android can work with decent performance with Raspberry Pi Model B+?
Straight to the point: none.
You can get maybe half-decent performance with Razdroid AKA CyanogenMod that's been ported to the first generation Pis (B+, B, A+, etc.). Usable, but not decent at all (for my standards). The cursor itself jumps around.
For decent performance, try to get a Pi 2. Android works with Berryboot. Just a bit of lag especially on anything graphics-fancy, but works.
So to conclude, yes. Android does run on first-generation Pis, but it's slow.