Originally Posted by .TNT.
Get the medium and eat a sandwich.
That's some pretty solid advice! We'd recommend a BLT, but the choice of sandwich is entirely yours...
On a more serious note; you'd be near the top end of the weight range for the Small so it'd be easier to initiate moves if you're not a very powerful paddler, but you may catch edges too easily and not get enough pop for aerial moves - whereas you'll be just under the middle of the Medium weight range, which should be more or less ideal so long as you have the technique and power to move the boat and make sure you outfit it correctly and snugly for yourself!
Most importantly though, demo both and see how you feel!
Hope that helps,