It’s unfair to Telemann to consider him inferior to Bach and Handel.
The problem perhaps lies in his wonderful altruism, attempting to write something for virtually every available instrument and also gearing his music to a broad range of abilities. He was really one of the first composers to have a real sense of responsibility towards the newly emerging amateur culture.
Telemann produced more music than Handel and Bach together, all of it worthwhile in one way or another; but his best music is obviously that which he conceived for the very best performers, and here his music almost always matches Handel’s in its variety, interest and subtlety.
Handel and Telemann knew each other early on in life, while they were both studying in Leipzig. It seems that they continued their friendship later in life, albeit in different countries, and Telemann dominated the music scene in Hamburg just as Handel did in London. They both participated in the newly emerging mixing of national styles that was developing in the early eighteenth century and both were keen to integrate traditional compositional techniques with more popular styles.