I would argue that ballpoint technology is inferior for several reasons. It uses ink that is basically a type of grease delivered by a tiny ball bearing with evenly but randomly distributed miscroscopic channels and is held in a socket. This has several consequences that affect the writing experience.
First of all, the oil-based ink eliminates almost all resistance of the pen tip against the paper, and because the tip is a ball, it is not inherently oriented in any particular direction. This makes the ballpoint harder to control unless you write on a stack of papers or a leather desk pad.
Secondly, because of the viscosity of the ink and the physics of the delivery mechanism, gobs of ink will tend to clot on one side or other of the socket and occasionally deposit themselves ungracefully on the page in the middle of your handwriting. This may be mitigated in higher quality, more expensive pens, but is the cost worth it?
Thirdly, all pens leak to some extent, but the operative term for ballpoints is "explode." When this happens inside the pocket of your bespoke Charvet shirt, it's either time to make a bespoke kite or find some other creative way to dispose of it so you can cross post pictures on every clothes forum on the web. More expensive pens are unlikely to explode, but if you happen to touch the tip of your ballpoint to your clothes accidentally, the resulting mark may be forever.
Rollerballs use water-based ink, which is less viscous. This means the tips offer more resistance and only go where you tell them, unlike a ballpoint, which will act as if it has a mind of its own. The ink will not clot, also, so your writing will be free of the little blobs where the ballpoint decided to take a shit. And if the ink gets on your clothes, you can wash it out with little trouble in most cases.
Fountain pens employ a leaf spring of gold (or sometimes stainless steel) mounted on a semi-cylindrical stalk of hard rubber (ebonite) with channels cut into it where the nib rests against it. These channels allow ink to flow out while air flows in as the ink is displaced from the reservoir. The mechanism relies on the surface tension of the water-based ink (which makes twirling a fountain pen a really bad idea). The nib is the heart of the fountain pen and can be extremely versatile depending on its geometry. Nibs can have varying degrees of flexibility and can come in a variety of widths and can be cut at different angles. A single nib can create a line that varies in width from beginning to end (a flourished line).
Many people complain that fountain pen nibs are "scratchy," but actually most nibs are very smooth. The fact is that people raised on ballpoints aren't used to a pen that offers enough resistance that some conscious effort must be put into controlling it. The result is that using a fountain pen for a while will actually improve your handwriting. Even a cheap fountain pen will write with almost no pressure, and you can therefore write for much longer without writer's cramp setting in. Also, since a nib is essentially a spring, it is basically a built-in suspension system, which makes the writing experience very comfortable and even sensual in some cases.
Do an experiment. Get a ballpoint, rollerball, and fountain pen -- the Parker Vector is an excellent cheap fountain pen that writes as smoothly and reliably as many pens costing several hundred $$ -- and write with each of them. You will probably notice differences somewhere along the lines of what I've described. Decide which works best for you in terms of feel and comfort, the type of line that pleases you most, and what flatters your handwriting.