It depends on your level of earnings. If you are both earning over 16,500, there is no benefit to splitting your tax credits, the end result will be the same. 16,500 x 20% = 3300 which is equal to the PAYE tax credit + single person tax credit.
If you are both earning over 35,300, there is no benefit in splitting your standard rate cut off point, the end result is the same.
If one of you is earning less than 16,500 you would see some benefit from splitting tax credits. If one of you is earning less than 35,300 and one of you is earning more than 35,300, you would see some benefit from splitting the standard rate band.