buttercream, so you need to talk to your baker about your options.
Let me just say that I make my own rolled fondant, so it isn't loaded up with artificial flavorings. Sometimes that's what makes people say that they don't like fondant, but not all commercial fondant tastes awful. There are different brands that people use, and some are better than others. If you're not sure, ask your baker to let you taste some of the type that they use so that you can preview what it will taste like. It's generally just sweet, though, like a candy clay.
Fondant also isn't supposed to be put on the cake in a thick sheet. It shouldn't be more than about 1/8" to 1/4" thick at the most. The cake should be iced with a thin coat of buttercream or another icing, then the fondant is applied over that. Some bakeries put fondant on a lot thicker than necessary, because that eliminates the step of smoothing out the base coat of icing.
There are two situations where you should use fondant, whether you like it or not. The first is weather, and the second is design.
Weather would be the deciding factor if you're having an outdoor reception during the summer. Fondant will help to keep your cake from looking melty and sad by the time the cake is cut and your pictures are taken. Buttercream will literally slide off of the cake if the heat is bad enough, and even if it stays put it can start to look sort of transparent. That's not the look that you want, in general, so if you're going to be outdoors talk to your baker about it.
Some people will say that they can "adjust the formula" for their buttercream so that it will hold up in the heat. That's basically saying that they'll reduce the butter in it and increase the shortening, which has a higher melting point. The only thing that accomplishes is making your cake's icing taste a lot greasier, so you have to decide if that's something that you want to do.
Another time that you'd need to use fondant is if you're going for a specific look, or a technique that works on fondant but doesn't work so well on buttercream. The example that comes to mind is brush embroidery, which technically can be done on buttercream, but looks more precise and delicate on fondant.
I had a client who wanted a specific brush-embroidered cake that she'd seen in a magazine, but she wanted it on buttercream. From speaking to her I realized that what she liked about it was the precision of the design, and I told her that it would be lost if I used buttercream. She really didn't want the fondant, but I didn't want to tell her that it would look the same when it wouldn't. She eventually decided to go with the fondant and was really happy with the result. If the design dictates fondant, you should go with fondant.
So when deciding about fondant vs. buttercream, keep an open mind, and realize that sometimes fondant is the better choice. If it means that your cake pictures will look better if the cake is still in one piece, and you'll get the design that you want instead of an approximation of it, fondant is probably the way to go.