I am short on time today, so just a quick comparison for you all to consider.
ESV Study Bible:
1:20 Angels of the seven churches might be human messengers, human pastors, or literal angels sent as messengers, but they are probably personifications of each church’s identity. Jesus will address his encouragement and/or rebuke for each church to that church’s angel. Cf. Dan. 10:13—14.
NIV Study Bible:
The first of several places where the symbols are interpreted (see also 17:15,18). angels. Either (1) heavenly messengers, (2) earthly messengers/ministers (see NIV text note) or (3) personifications of the prevailing spirit of each church.
NLT Study Bible:
1:20 John is to record what he sees because Revelation is an instructive word for the churches. – The angels (or messengers; Greek angelos) of the seven churches could be (1) the guardian angels of these churches (cp. Matt 18:10; Acts 12:15); (2) the leading officials of the churches (cp. Matt 11:10, where “messenger” is angelos); or (3) a personification of the ethos of the church. The best understanding is probably a combination of 1 and 3.