I'm an Android junkie. Had the iPhone 5c briefly for work (it was halfway decent for the limited task of phone calls and email) but I despise Apple with a passion for a lotta reasons I won't go into here. Some company-related, most tech-related.
That disclaimer aside, I've had the Galaxy S3, S4 (work), S5, S6 (current work phone), S7 Edge, S9 Plus, and later this week will be swapping the 9 for an S10 Plus. From the S7 forward, the camera has been one of the biggest driving forces for me to get the Galaxy. Autofocus was game-changing in the S7 generation, and image quality has only improved from there. No phone can compare to an SLR, and if feasible, I'd much rather have my Canon 80D and 70-200 f/2.8L IS. But more often than not, I don't have that option and find the Samsung-of-the-week to be an acceptable stand-in. =) The latest Galaxy has, predictably, perched itself at the top of the DXOmark ranks yet again.
Gigantic battery (4100mAh if memory serves) is a major bonus too, especially when paired with the latest power optimizations in Android 9/Pie.
Otherwise, just about any modern smartphone can handle Strava duties.