Smartphones are available in different sizes ranging from smaller to bigger ones. Some people prefer to use small and medium screen size phones as they become handy and easy to use. While some prefer to use phones with bigger screen size for a better display and for better visual experience i.e.watching movies, videos, playing games etc.
I prefer screen size of 5.5 inches.
I think 5.5 Inches smartphone is better for others sizes.
I think 5" Size is the perfect for daily use.. it will be comfort in your hand, in your pocket and proper screensize to display images and emails and videos.
More than 5.5 inches should be considered phablet. 5.5 inches fits well in pocket.