mozart is the most complete artist of the three.
he wrote many masterpieces in all composition types. bach's success is largely sacred music and concertos. beethoven's best works are largely the symphonies, concertos, and chamber music plus sonatas. that makes him even more diverse than bach. but mozart was accomplished at everything - sacred music, symphonies, concertos, chamber music, sonatas, plus all those amazing operas. however, if one has a preference for the baroque the composer of choice will be bach and if romantic, then beethoven. but mozart is in the middle position and did everything they did plus more.