Healer, tank or dps?
Healer, healer, healer.
I feel seriously out of my element when I'm not able to heal myself. I've struggled to try to play as a tank and as dps, but I've always come back to healing.
My first toon to make it to high level was a Warlock. In retrospect, I now know what types of toons are more easy and more difficult for me to play. Warlocks were and still are very hard for me. I did try my hand at tanking via a Paladin that I promptly abandoned after reaching level 80, and a Death Knight that still isn't even level 80. I'm currently in the process of attempting to learn to be a dpser (see my many alts).
Since I'm no longer focusing on end game raiding but more on the journey, I think that my time as purely a healer may have come to an end. That said, as a dpser or a tank, my primary goal is always survival, whether it be in a raid or pvp setting or just out questing. There's a reason why I tend to follow roads rather than cross country. The lessons I learned leveling my squishy Priest as Holy stay with me still. Never pull more than one mob or a quick death may ensue.