The instrument that the user is most interested in playing is usually the easiest instrument to learn to play. A willingness to learn also aids in the ease of learning to play a musical instrument.
Two instruments that are well-suited for beginners are the piano and the guitar. The piano is classified as a fundamental instrument and is suited for people of all ages. The six strings on the acoustic guitar are easy to navigate for most people and can be self-taught through instructional videos and books.
The flute and clarinet are part of the woodwind family and also considered simple instruments to learn. The drums and xylophone are also good instruments for beginners.