In Milton (Erdman plate 22  Lines 53-63: Blake referred to Wesley and a confederate, Whitefield, as the two witnesses mentioned in Revelation 11:3 As far as I know, Blake never mentioned Fox, but one may consider Blake's term in The Divine Image, 'Turk and Jew' in the nature of a quotation from Fox.
Condemning those Christians who deny the light Fox wrote, "you make a profession of Christ in his flesh, and will not own his light, which enlightens every man, which is the life in him, you are as bad or worse than the Jews, Turks, or Indians; for they will confess to that light which does condemn evil in them, but you make a profession, of Christ in the flesh, yet deny his light, which is life in him; and the Jews, Turks, and Indians, will confess to the light that does reprove them....." (from The Works of George Fox, Vol 5, p. 200)
Fox, and Blake as well, had only contempt for Established religious practices, ceremonies, dogmas, special days, etc.; for them the Spirit, the Light was what matters.
Two dissenters in two centuries provided a creative leavening that may have saved England from complete disorder and chaos. Things there were bad enough anyway. Religious dissenters beheaded England's king in 1651 just as Fox was beginning to
spread the Light of the Prince of Peace; he would "remove the cause of War", recognizing that of God in everyone.
Fox went to the steeple houses to denounce the hireling priests---and spent many a day in prison (something our poet fortunately escaped).
The 18th Century dawned; William and Mary brought a semblance of order into England, but political, economic and religious corruption abounded.
Wesley was born; he didn't denounce hireling priests; he just showed a better way. In that day the churches, the cathedrals, had minimal congregations; the average Brit would not dare to enter the place; it was reserved for the uppers, and virtually the entire population held the 'state church' in low regard. On Sundays ordinary men attended saloons, bear baitings, cockfights, you name it. Wesley went to these places, to the public square, to gathering places of miners and blessed them with the love of God. He preached to thousands in those places while a handful of pious souls went to the cathedrals. He saved England from a revolution.
All this was part of the backdrop in which William Blake was born and grew up; Wesley died in 1791 when Blake was 24.
In England Fox and Wesley were the foremost witnesses to the kingdom of God in the 17th and 18th centuries. Blake was the third one; in the 19th century.
Here are some attributes the three men shared:
anti political and religious corruption
anti economic exploitation
for food for the poor
for Universal inclusion