It's easy to get pulled into the phone specs war: single-core or dual-core processor? 3G or 4G? But today's smartphones are mostly big screens and it makes more sense to pay attention to how good apps, pictures and video will look on those screens.
Display size/resolution: If you intend to surf the Web on your phone, use the calendar and organizer, or compose and read a lot of e-mail and text messages, make sure the screen is up to snuff. Is it big enough for you to take full advantage of the phone's features? For browsing the Web or editing office documents, a screen that measures less than 2.7 inches diagonally will feel very cramped.
Consider the screen's resolution, too. The higher the resolution, the sharper your videos and photos will look. Also factor in what kind of screen technology it uses. AMOLED displays perform well in sunlight, but many people think they make colors look oversaturated. qHD displays (whose resolution is one-quarter of a full-HD 1080p frame and three-quarters of a 720p frame) generally look the best in video playback and games.
Being able to take control of the screen's contrast and backlight settings can also be important, as phones have noticeable differences in their default display settings. If your phone allows you to adjust contrast and brightness, text and graphics can be easily viewable in well-lit places, and you can also save battery life in a pinch. Related: 10 Ways to Boost Your Phone's Battery Life