What is the best type of mortgage loan for the lowest monthly payment?

30 year fixed? 2/1 ARM? I need a loan with no PMI and low points and the lowest possible mortgage payment a month. What Im working with:

Credit score 600
Annual assets (Salary) 34500
Monthly Debt: 70
House loan amount: 106000
Available to put towards closing costs (Including down payment) 12000

Any ideas?