There's no right or wrong answer to this question – It depends on your own personal circumstances and the choice is up to you.
If you're the type of person who'd rather know exactly how much your mortgage repayment will be each month, a fixed rate mortgage might be the better option for you. On the upside this gives you peace of mind, but the down side is that if interest rates go lower, it means you could end up paying more interest on a fixed rate than you would've had you opted for a variable rate mortgage. You may also have a breakage fee if you choose to exit the fixed rate contract early for example if you sold the property or want to make a lump sum payment to the mortgage during the fixed rate contract period.
With a variable interest rate, your repayment may rise and fall in line with interest rate changes, so you don't have that certainty as to what your mortgage repayment will be each month for the next few years. A variable rate also allows you the freedom to modify your mortgage and your mortgage repayment should you wish to increase the monthly mortgage repayments or pay a lump sum off the mortgage. There are no breakage fees or penalty should you wish to pay off all or part of your mortgage early during the mortgage term.
Mortgage Master will mention that having a bit of both is available with a split mortgage.