Really think Flappy Bird is harder on an iPhone 4 than any other.
My highest on a friends Samsung Galaxy is 140 (had 10 goes and was into the 100s 4 times). Highest on girlfriends iPhone 5 is 101 whereas on my iPhone 4 (which I've probably had 100times the tries on) is only 54.
iPhone 4S must be the worst, on 12.