Marines vs terran is a total waste of money. 12 tanks + 12 golliaths can probarbly kill 100 marines
I tend to mix in wraiths vs terran sometimes, depends on the map. Ghosts with lockdown are very hard to use because tanks waste them before they can lock down too many BCs, and it is usually more effective to get BCs. I get ghosts if i see that the opponent has a better echonomy than me and is able to make more BCs than me, but in most cases i make BCs in stead.