Depends - adjustable only if you plan on paying off the loan before the next adjustment period. For example we once re-financed with a 5 year adjustable loan. We planned on selling on how in about 5 years so it made sense to get the lower interest rate.
However, if you plan on staying in your home or not paying off within the adjustable period, with interest rates as low as they are now, it is highly likely the rates will increase. In this case, you would get a lower rate, but it will be short term. It could even increase to an amount that would be higher than the current fixed rate amount. In the long run, for most people, a fixed rate is a better option when interest rates are currently very low.