Although you have received two posts on the benefits and technical aspects of HF, the abbreviated answer is we (almost) all use VHF all the time. Most aircraft don't even have HF radios fitted, and most pilots from basic PPL through to commercial pilots will go their entire careers without ever using HF.
VHF is more reliable, less prone to noise and distortion, has more channels available, uses simpler equipment, and all-round is always going to be the radio of choice. There's only one catch - it is a "straight line" transmission and is therefore limited in range by the horizon. That is not a problem in the populated parts of the world, but for operations in some oceanic airspace, or over some sparsely populated areas, you might be out of range of VHF stations. Only then will you resort to HF, which is why HF ops are a "specialist" kind of operation that most pilots will never need to bother with.
You may still need to answer an HF question in your exams, however
