I'm biased because I'm a tank (thereby not having to work with other tanks in DF very often) but I'd rather have a good tank. It's really six in one hand, half dozen in the other though. Tales of horrible wipes to Garuda Normal mode because the tank doesn't understand to avoid the pillars or because the healer doesn't know how to dodge mistral after dying to it a dozen times.
On some fights you can skirt by without one or the other. I've had numerous near-wipes at Isgebind that turned into wins after the healer died because of abusing the enormous hate-lead a good tank will have and then cure-bombing with convalesence up and stone-skinning remaining party members to mitigate Rime. I've also seen SCHs take down Coincounter with PVP tactics of sprint-dot-run after everybody died to 100-Tonze swing.
On some fights you can skirt by without one or the other. I've had numerous near-wipes at Isgebind that turned into wins after the healer died because of abusing the enormous hate-lead a good tank will have and then cure-bombing with convalesence up and stone-skinning remaining party members to mitigate Rime. I've also seen SCHs take down Coincounter with PVP tactics of sprint-dot-run after everybody died to 100-Tonze swing.