If you just want to have "fun," whatever you think that is, then it literally doesn't matter what class you choose. At all. In fact it doesn't even matter if you play this game. This game isn't required for fun. There are many things in the world which can provide that experience. WoW isn't the least bit relevant or necessary for obtaining fun in that sense. The reason is because if you are determined to have fun, most likely you will enjoy whatever you eventually decide to do.
In actuality you may accomplish very little, if anything, but with the proper attitude you're virtually guaranteed to feel great about yourself along the way, even if all you do is passively gawk at other people's journeys from some mostly stationary vantage point, i.e. Stormwind.
On the other hand, if you have a goal in WoW you'd like to achieve, some healing classes can in fact be better than others in pursuit of said goal. But its doubtful you could trust anyone's word about what would help you, personally, reach your goal.
Its not that people are liars, its just that nobody has to live with the thing inside your brain like you do. Nobody understands you like you do. The only one who is going to be able to make the best choice about which class works best for you under what conditions is...you. You're the only one who can decide.
So take some responsibility, and choose.
Or, leave it up to someone else to decide your fate. If you go this way you may end up happy, or miserable, or anywhere in between...but in any case you left yourself at the mercy of someone else's decision making capabilities. Perhaps you don't care about WoW that much if you want other people to make choices about it for you?
You should be warned; if fun is your primary goal, there are many systems within WoW's gameplay designed to get you to behave in a specific way. If you find the idea of your freedom of choice being limited in this way distasteful, its probable you won't have fun in WoW no matter what you do, as the pervasive hum of someone else's decisions about how and in what ways you should spend your time will constantly surround you.
Especially, take note of the first time you get quest to kill X number of creatures, or return with X number of items. You will be asked thousands, perhaps tens of thousands, of times to perform that action in WoW. In fact for the casual player, it is that behavior above all others that is being designed as the pinnacle expectation of gameplay activity for each log-in day.
That is but one of the costs of buying in to this game environment.