If you want a good battery life, get a Sony phone - that seems to be the overarching conclusion from several graphs plotting how a few popular phone brands changed in terms of handset endurance since 2011. A very welcome trend of a constantly increasing battery life on average can be observed, too.
Sony is the big outlier here - starting at the bottom in battery endurance in 2011, it has constantly strived to optimize power consumption of its components, to the point that it is now the phone maker offering the best battery life from all major players, with most of its handsets lasting about two days on a charge with normal usage. The next outstanding performer is Samsung, which has also done wonders for the battery life from its handsets, especially given the relatively small capacities they are outfitted with.
Unsurprisingly, given that phones were getting ever-larger until this year, battery capacities have also grown significantly, and the author found this variable to be the one most positively correlated with the better battery life we have now on average. Granted, there is negative correlation between screen size/resolution, and battery life, but it is more insignificant, compared to the positives of the increasing battery capacities during that time.
Apple is actually the only one of the major players, whose endurance per mAh has fallen for the past four years or so, which is exemplified in our own battery benchmarks, too - the iPhone 6 will still last you about a day, as the iPhones before it, though it has a larger battery than its predecessors.