I am not going to tell you how much I spent on this ring
I won't tell you how much I spent on this ring
Which is the best sentence ?
I think in the first case the decision has made before speaking (it has already been planned before and it is an intention no to tell the price of the ring ) so going to should be better, but it could be also an instant decision so will could also be good . May be will is stronger than going to and last "for ever" whereas going to is limited in time