There are many Instruments to choose from, all covering a wide variety of genres, sounds and difficulty levels so if you're interested in starting your musical journey it might seem overwhelming to know where to start.
For younger students, we have found that picking an instrument such as piano or drums may be better as it is very easy to get a sound out as you only have to hit a key on the piano or hit a snare on the drums. If a younger student's first experience with learning an instrument is less frustrating and more positive, then it would allow them to develop a love for music and sets them up for a better learning experience in the future. An instrument such as the guitar would have a steeper learning curve and would require you to have more dexterous hands which may be difficult for children who's hands are smaller. As a result it is very hard for beginners to even get a note out and as a result it may be frustrating and put them off further pursuing music due to a negative experience.
An important thing to consider would be knowing what type of music you want to play and what type of musician you want to be as all different instruments have different unique roles to fulfil. For example if you're more of an energetic, confident person who loves to be the centre of attention then the electric guitar may be right for you. It is often considered the 'heart' of a band, as it carries the main role of delivering those catchy melodies or riffs that people love. If you're more of a laid-back person who prefers not to be in the spotlight but wants to be in more of a supportive role and still have a massive role to the sound of the music you're playing then the bass guitar or drums may be right for you.
If you prefer a more classical approach to music and instead would like to play music that would emotionally move people with beautiful melodies then the piano or violin may be right right for you. But another thing to consider would be that classical instruments are much more expensive than your typical band instruments and require a lot more maintenance. They also often are much harder to play and have a very steep learning curve but if you're passionate enough to push through then absolutely go for the classical route.
There are many things to consider but the most important thing would always be how much enjoyment you get out of playing your instrument so I would recommend being open to trying a wide variety of them. Another thing to keep in mind is that the amount of effort you put into your playing is directly proportional to your skill so no matter what you play, as long as you hard working and happy then you can play the music you and others love.