St Davids Cathedral in Pembrokeshire, the Tabernacle Chapel in Llanelli and St Melangell in Llangynog, Powys are among entrants in the National Churches Trust's SacredWales poll.
Vice President of the trust and broadcaster, Huw Edwards said: "The churches and chapels of Wales are some of the most beautiful religious buildings anywhere in the world.
"Now, 'Cymru Sanctaidd' - 'Sacred Wales', is giving you the opportunity to choose your favourite."
The entrants have been chosen with the help of religious and heritage organisation from 4,500 Christian places of worship across Wales. They also include the Tabernacle Chapel in Ruthin and St Sannan in Bedwelty.
Online voting closes on 31st August. The winner will be named on 28th September.
SacredWales is also trying to highlight to growing problem of funding and looking after churches and chapels across Wales, as congregations continue to shrink.
Huw Edwards went on to say: "We should all care about the heritage of churches and chapels which help tell the story of Wales. So let's work together to keep them alive."
"If you're looking for a venue to hold an event of a concert or community activity, why not pick one of your local churches or chapels. If you're any good at DIY, why not volunteer with some repair work."
Earlier this month, the National Churches Trust published the Supporting Places of Worship in Wales Survey 2017 report. It highlighted a severe shortage of volunteers, a lack of fundraising skills and a shortage of cash to carry out maintenance.
Huw Edwards added: "...if you're simply looking for a day out in another part of Wales, why not pop into a church or chapel and discover the fascinating history."
"The religious heritage of Wales belongs to all of us. So let's celebrate it."