Overall: if you want to see the sun setting behind buildings, then Oia is perfect. if you want to see the sun setting on the water, the angle of Fira will be better most of the year.
The Kardashians stayed at Celestia Grand (back when it was part of neighboring Volcano View Hotel) in Santorini during their vacation in Greece. It's an awesome luxury villa collection, located south of Fira (about a 30 minute walk into town or an easy ride with a taxi or their complimentary shuttle).
With whitewashed houses in complete harmony with the volcanic scenery, it is without a doubt that the villages of Santorini were built to meet perfection. Such an example is the beautiful Oia village, known for its neoclassical mansions, small churches, narrow cobbled paths, and colorful houses.
It has become globally famous for its authentic Cycladic beauty, whitewashed houses, labyrinth-like alleys, and amazing hotels, even though the number one thing Oia is renowned for is its magical sunset.
Walking from Fira to Oia is one of Santorini's top experiences. Hike along the rim of a caldera, explore the towns of Oia, Imerovigli, Firostefani, and Fira, and enjoy some of the most beautiful views of the islands. If you go the entire distance, you will walk just over 10 km (about 6 miles).
The hike between Fira and Oia follows the rim of the caldera. The views are stunning. It's easy to do the hike without a guide but a walking tour can make it more interesting.
Watching the stunning sunsets is a requisite activity in Oia. And though you could really stop just about anywhere to see it, the most popular place to watch the sun go down is at the castle. It provides a sweeping view of the ocean, speckled with other Greek Islands.
Both Imerovigli and Oia have some views towards the west, but I think most will agree that the actual sunset from Imerovigli is a little better than Oia. It sits higher on the caldera, is directly facing west, and has unobstructed views. You can also have a view of Skaro Rock and Oia in the distance which is magical.
Oia is world famous for its spectacular sunsets. The cascade of whitewashed buildings, dotted with windmills and blue dome churches, form a stunning backdrop for photographers. As the sun goes down, these buildings glow in pinks and oranges and yellows.
You don't need to go as far as Oia though, as Fira does a pretty good Santorini sunse of its own. It's also easier to find a quiet place – the busiest spot is the area in front of the Orthodox Cathedral but there are plenty of other sunset viewpoints.
Oia is typically thought to be the more beautiful and romantic town on the island. I stayed there on my honeymoon and wouldn't have changed it. It was amazing at night to see all of hte people from the island come to the area around my hotel to see the sunset - when this was the view I had from my bed.
The hiking trail from Fira to Oia is just under 10.5km (6.5 miles). Part of the path is similar to a sidewalk, parts are cobblestone, and parts are a dirt path. There is a good climb in both directions.
Three Blue Domes Santorini - MonumentsThe most photographed Santorini blue domes churches are located in Oia and are the churches of Agios Spiridonas (Saint Spyridon) and Anastaseos (the Church of the Resurrection). Both are built at the edge of the cliffs right next to one another.