Should I pay off my vehicle or one of my mortgages?

[NunyaBizzness]

-$40000 truck financed at 6.9% fixed APR for 84 months (less than 6 months old)
-$30000 2nd mortgage at 9.5% fixed APR on a 15 year balloon (had for 18 months)
-$125000 1st mortgage at 7.125% fixed APR on a 30 year conventional (had for 18 months)
-$13000 boat financed at 5.9% fixed for 120 months (4 years down, 6 years to go)

Amounts above are current estimates, not representative of the original loan balance.

My gut reaction is to pay off the 2nd mortgage first because it carries the highest interest rate. However, it's my understanding that the interest paid on my mortgages is tax deductible, so would it be smarter to pay the truck off first? I've already talked to a CPA and a financial advisor and am only being told that I should do what I'm emotionally comfortable with. I could care less about emotion...I want to do what is financially sound. So what is the smart move here and why? My taxable income between now and October 2008 will be approx. $166,000 USD. Thanks!