Here's an interesting stat - among Google Pixel 3 and OnePlus 6T buyers in Q4 of 2018 in the US, the most were former Samsung owners. Less than 20% were iPhone users. Now let's clarify a bit. According to Counterpoint Research data, some 51% of Pixel 3 buyers in the States were owners of a Galaxy smartphone, however 31% of them owned a three year old Galaxy S7. While 37% of OnePlus 6T buyers came from a Samsung phone, many of them used either a Samsung J2 Prime or the aforementioned Galaxy S7. Also worth noting is that 80% of the Pixel 3's sales came from owners of Android devices...
Source: https://www.gsmarena.com/counterpoint_pixel_3_and_oneplus_6t_adopters_came_over_from_samsung-news-36463.php