Some general considerations - The Canon EF 100-400mm f/4.5-5.6 L IS USM Lens is best suited for wildlife and sports because it is reasonably fast, sharp, and accurate, but has the very wide range of 100-400mm. This allows you to quickly switch between subjects near and far, without switching bodies or lenses. This is an older lens in the lineup, as such its IS does not quite perform up to the standards of the newest lenses, but overall this a fair value for the price they are currently asking for it.

The Canon EF 70-200mm f/2.8L IS II USM Telephoto Zoom Lens is at the high end of the price range, as such it provides excellent image quality, maximum aperture capabilities, and image stabilization. This is an excellent lens for portrait photography, almost a requirement for indoor portraits for most professionals. This would be my pick out of the zoom lenses you mentioned, but it also demands the highest price. You could look at the still excellent version one of this lens to save a bit of money.

The Canon EF 70-300mm f/4-5.6 L IS USM Lens fits between the previously mentioned two lenses. It doesn't have quite the range of the 100-400, or quite the aperture of the 70-200, but it is kind of a best of both worlds. It is the middle of the road for weight as well. One consideration is weight, this is not as heavy as the 100-400, but not as light as some of the 70-200 options(especially non IS). This lens has excellent 4 stop IS and a great deal of newer features that the 100-400 simply does not offer.

Overall, the Canon EF 70-200mm f/2.8 IS II USM is probably the best lens of this range generally speaking. It also has the highest price. If you want to stay within your price range, consider the Mk I version or the non IS version. If you add a teleconverter to this lens, it turns into a fantastic sports and wildlife lens as well, so that pretty much covers all of the lenses mentioned here.