This is another easy one. The answer is based upon your own circumstances and goals.
If you know you will be in the home for only a short time, say for example three to five years, then you may want to consider an adjustable rate mortgage which keeps the intrest rate static for a certain number of years before adjusting to the new rate.
If your plan is to live in the home for a long time, then it may make sense for you to select a fixed rate mortgage.
Another scenario might be if you know your income will adjust upward after a period of time, in that case you may want to consider an adjustable mortgage for a few years to help keep the payments in line with your current goals and then refinance the loan later into a fixed rate product then.