The phone quality on the iPhone 5s is excellent. We tested the phone on Sprint's network throughout the Los Angeles area and the clarity of the caller on the other end was fantastic. The iPhone 5s speakerphone is decent, but sounds a little quiet. We often had to move the speaker to our ears -- this is something we never had to do with Android phones.
The phone quality on the Samsung Galaxy S4 is also great, at least on both Sprint and AT&T's network. The speaker on the other end sometimes said we sounded slightly muffled. The Galaxy S4 has a better speakerphone than the iPhone 5S, but it can still use some extra volume.
There is no clear winner in the Phone category; the iPhone 5s and the Galaxy S4 both offer excellent clarity.
The battery life on the iPhone 5s isn't perfect, but it's better than it was on the iPhone 5. We browsed the Internet with Sprint's LTE network for about an hour, listened to music for 2 hours, streamed a video from Hulu Plus for 45 minutes, talked on the phone for a half hour, and used the GPS for a 20 minute trip. The battery lasted us almost 9 hours. Doing the same on the iPhone 5 lasted us 8 hours. The iPhone 5s battery will definitely last a full day for most users.
The 2600mAh battery on the Galaxy S4 not only lasts a long time, but is removable, unlike the batteries in the iPhone 5s and HTC One. Most users will definitely get a day's use with the Galaxy S4 without having to recharge the unit.
We will have to give the prize to the Galaxy S4 in this category, especially since the battery is removable.
Picking the overall winner is difficult. The iPhone 5s is built very well and is very easy to use. However, we can do more things with the Samsung Galaxy S4. We also don't have to squint our eyes when using our Galaxy S4 like we do with the iPhone's small screen. The Galaxy S4 is our overall choice, but not by far.