Just had an epic iPhone 5 vs Galaxy S3 comparathon with all my cousins etc present. Pretty much a unanimous win for the S3, but the weirdest thing was I was there defending the iPhone 5.
I think the biggest selling point is the screen size. Coupled with the actual blacks as oppose to greys (comparatively) of the 5, vids just look much better. Using the YouTube app the vids are much bigger and more detailed on the S3. Loaded N***as in Paris Live and for some reason it was letterboxed on the 5 and full screen on the S3.
Video loading speed was much quicker on the S3, with the 5 stalling a lot.
Crunchyroll vids looked better on the S3, I think they may have been direct flash vs iPhone specific.
Speaker wise I think the 5 is ever so slightly louder, but I expected it to be much louder. With both on at max volume, you can't really hear one especially over the other. It's close, at least it was in our already fairly noisy environment.
Camera quality wise, the 5 is a bit brighter in low light, and might be a touch less noisy too, but the S3 shots seem a tad more detailed. 5 was a touch softer in low light.
Video quality (again low light only) S3 seemed better. Slightly less bright but far more detailed and better much wider angle. Both seem smooth.
Both mess up on white balance camera vid wise. The 5 is too saturated and warm, the S3 too cool and less colourful.
Panorama overall was better on S3. With the 5 you're stuck with portrait, S3 you have landscape too. Again, S3 is slightly darker but seemed to pick up more detail. Both stitched really well.
Web wise, S3 was only on ICS and I think the 5 was marginally quicker, both being very quick. S3 showed more info, but whites were less bright, with blacks superior. 5 had more accurate whites but less accurate blacks.
We only tested one other app, auto rap, and I think it processed faster on the S3, but I fully expect it to be a software update thing for the 5.
In the time we used both phones, the S3 used about 4% less of its battery. Both lost little. Was not really a valid battery comparison.
I think the video at the same time as Web browsing thing was an impressive feature of the S3, as was smart stay which seemed to help. Main thing was that media just seemed more impressive on the bigger and what looked to be more detailed screen (at least with the media we played).
I think both are amazing though, but my pick will remain the S3. I expected more from the 5's camera and speakers tbh, but it might just be the conditions.