Apple is known for its brand and has been producing some good stuff from long time.
I had been using iphone 4, then upgraded to 5s as I was an apple fanboy. Both of the phones were great, but since the launch of new iphone 6, 6s and 6s plus the technology has been upgraded also. Iphone 6 and above is bit expensive but apple charges that money as they have put a lot of RND in there development.
The things I really like in iphone 6 is the smooth performance in ios 8.0 but had some bugs, now updated to ios9.0 all buggy things have been resolved .
The battery backup is also good even when using 3g on for full time, screen size is also big as the many new smartphone come with big screens. The best thing I like in apple is that they make there own processors and not like other brands in cellphones who use different processors from different manufactures . The phone does not heat up in normal usage and works smooth . This time camera has been updated also and many photographers must be liking it who like to click pictures with there smartphone .