Threw me for a moment there, Snuffy, with that B... I think it's safe to say that Watts and Wesley were admirers of each other's work. They were not direct competitors; Watts' active hymn-writing career was pretty much over by the time Wesley came on the scene (in the late 1730s); he died in 1748. For that matter, I think most of Wesley's major hymns were written early in his career, too. Let's see...

Of the 6,000 hymns Wesley is said to have written, and less exhaustively of the more than 200 listed on his bio page at the CyberHymnal, I list here, with their dates as best I can ascertain, the 21 that I consider major (doubtless there are a few others that I simply didn't note while skimming, or that the Cyberhymnal forgot to list, and a couple are only partially our doubtfully Wesley's—hence the occasional trailing (?)—but this should do for starters):

And Can It Be That I Should Gain? 1738
Christ the Lord Is Risen Today, 1739
Come Away to the Skies, 1755 (for his wife on her birthday)
Come, O Thou Traveler Unknown, 1742
Come, Sinners, to the Gospel Feast, 1747
Come, Thou Almighty King (?), 1757
Come, Thou Long Expected Jesus, 1745
Hail the Day That Sees Him Rise, 1742
Hark! the Herald Angels Sing (Hark, how all the welkin rings), 1739
Jesus, Lover of My Soul, 1740
Lo, He Comes with Clouds Descending, 1758 (revising Cennick)
Love Divine, All Loves Excelling, 1747
O for a Thousand Tongues to Sing, a cento from a poem of 1739 written
     on the first anniversary of his conversion experience;
     some of the omitted material is worth reviving, perhaps in a separate cento
O Love Divine, What Hast Thou Done, 1742
Praise the Lord Who Reigns Above, 1743
Prisoners of Hope, Arise, 1749
Rejoice, the Lord Is King, 1744
Soldiers of Christ, Arise, 1741
'Tis Finished! The Messiah Dies, 1762
Where shall my wondering soul begin, 1738
Ye Servants of God, 1744

As you can see the vast majority were written in the first 11 years of Wesley's active hymn-writing career, i.e. 1738-1749.

Haruo