personally i would go with the zxr6 they style is great the power is great for a beginner (no worries of over powering but there if you need it)
the 650 is as well a nice bike..a little less power then the 6r however a great ride. the 250's on the other hand are good bikes yet as a rider myself i will tell you, you will want at least a little more power later down the road they do however get a little better mpg but not much. new versions top out around 100mph they do have some passing power but again not as much as the other two.
with that said
between the two i honestly believe you would be happier with the 650r
good mpg, smooth power (not to much but its there.) a much better cruiser.