Most people do not get the leg development they want because they don't understand the anatomy of muscles in the legs. The legs are an endurance muscle. They have a large composition of slow twitch muscle fibres. Most people only train in a 8-12 rep range. The problem with that is it won't stimulate the slow twitch muscle fibres. In order to fatigue the slow twitch muscle fibres, you need to train in a rep range of 20-100.
Use a variety of exercises to fully develop the legs but make sure to add in some 'burn out' sets at the end of your workout in a rep range of 20-100 to stimulate the slow twitch muscle fibre. You will feel a burn like you have never experienced before.
Think about it. Look at the legs of a cyclist. They don't squat or lift weights at all but they always have extremely impressive leg development. That's from all the high rep work they constantly do when cycling.