Being a tank is a lot of fun, but it certainly puts a lot of pressure on you. Because you are the one facing off with the enemy, you tend to become the default leader, and therefore the one that blame and scrutiny immediately falls on when things go wrong. You're armor is too weak or you didn't hold agro well enough etc. The tank role is the typical male role, to lead, protect, strategize and take risks. Good tanks are like successful entrepreneurs, receiving praise and attention for fulfilling their role so well. Bad tanks are like the guys whose wife divorces them when they lose their job.
Dps was always the least appealing to me, I would say it is the beta male role equivalent in the MMORPG world. As a dps you are necessary, but your job is fairly easy and straightforward, thus many people want to fill that role and it becomes the least valuable role. If you've ever tried to find a pick up group as a class that is solely dps, you know exactly what I am talking about.
When I play as a healer I enjoy myself, but it is just a mild sense of satisfaction because I feel that our success was mostly because of the other players in the group. If the MMORPG party were a couple, the healer would be the housewife who feels under appreciated, but sticks with it for the pay off.
When I play as a tank my emotions become extreme. If a difficult battle goes smoothly, I get a rush of satisfaction. Even if I understand on an intellectual level that we were successful because we worked as a team, it's hard to fight that instinctive feeling to take most of the credit because I was the one putting myself most at risk. On the other hand, when things go poorly, it's easy for me to feel guilty, that the failure was all because of me, since I have the most control over the encounter.
I've enjoyed playing as a dps, but it makes you feel like a mercenary, a replaceable cog in the party machine. Dps classes are the most popular because they make you feel powerful with big damage numbers and fancy attacks, but over time the monotony of your role and your own replacability will start to bother you. You just don't feel as needed as a dps.
I suppose I am fairly feminine, but I am still a man, so the hybrid classes that can step in and contribute DPS or another unique ability, like mana regeneration, when necessary are the most appealing to me. Shadow priest and Shaman in World of Wacraft and Red Mage in Final Fantasy 11 were my favorites.
It's interesting that Final Fantasy 14 was originally a game that tried to minimize party roles, and it was an absolute disaster. It seems that people tend to prefer more clearly defined roles, in life and in online games. The rise of feminism has led to the current chaotic state of affairs between men and women. We now have the freedom to chose our own role in life, but our culture and biology still push us to behave in certain ways. I believe problems will persist until men and women learn to fully appreciate the value of each other's traditional roles and chose to be open and honest, to negotiate with their partners about what role, or combination of roles suits them best.