Your character’s class is essentially what they do. It gives them the set of skills they start with, as well as their suite of powers. As someone who is usually a DM, I don’t get many chances to play as a PC, but when I do, it is most likely that I will ply as a fighter/cleric.
I like being the healer because it really helps me stay engaged with the game even when it isn’t my turn. Also, it mkes me feel like my character is really important for the group. The party needs a cleric, and if that cleric can kick butt at the same time, it’s that much better.
While many people like to play characters that are “broken men with a haunted past”, I prefer a character that’s a bit less grim and gloomy. A cleric allows the grim and gloomy guys to have someone to talk to and give them a shoulder to lean on. The cleric gives the party not only a longer life, but a happier one as well.