My top 2 composers are Beethoven and JS Bach. Really, they are almost interchangable depending on what mood I'm in.
I also like
Haydn. Poor Joe doesn't get as much recognition as he should these days. He's barely a millimeter behind Mozart in talent.
Mozart
William Byrd (highly underrated keyboard guy, but his masses get a bit samey)
Domenico Scarlatti.
Handel
Chopin , although I have to be in a receptive mood. he can bore me if I'm not in the mood for piano music.
Rameau. He's on the bridge where the Baroque is merging in the Classical period.
Brahms, although to be honest almost all the Romantic era composers like Schubert, Mendohlsson etc are about equally good.
I haven't yet explored the 20th century Russian composers like Shostakovich etc so I can't rate them.
I also enjoy many of the French composers of the late 19th century like Faure, Debussy etc. but you can only fit so many into a Top 10