Tenor guitar has been my first instrument of choice for some years now. As has been already said, there are many tunings possible. My preference is DGBd - open G major chord. With this tuning, you can play chords in any key without a capo - the neck is only 1.125" wide, so a barre is really easy across all four strings. However the main benefit for me is to be easily able to play melody in D or G more or less in 1st position. Tenor guitars are naturally very quiet, but with a pickup, can play in a band, on rhythm or on melody.