It totally depends on your viewing habits, and then only you should go for a pick. The three types of resolution that are seen in LED TV and are as follows:
1280×720 pixels or 720p
It is commonly found in HD or HD ready and in the most budgeted TV. As the world technologies are growing day by day, this one comes under the entry-level today. They are generally found in small screens like in the 32 inch LED.
1920×1080 pixels or 1080p
This is the middle ground of screen resolution. It is common in the Blu Ray Format, and the majority of cable is found on this resolution.
3840×2160 pixels or 4K
It is four times than the full HD screens, and you will see the sharper and the perfect picture. With the streaming content like Netflix, Amazon Prime Videos you can record videos in the 4K. You can play these videos in full glory.