As of August 2015, the most popular texture packs from Planet Minecraft are LB Photo Realism Pack 256x256, Sphax PureBDCraft x128, oCd Texture Pack 1.8, Dokucraft: The Saga Continues [Official] [32x] 1.8.1 Dark/High/Light and OzoCraft (1.8). Texture packs are user created content that change the look of Minecraft.
The most popular texture pack, LB Photo Realism Pack 256x256, makes Minecraft look as realistic as possible. The textures in the pack change grass, water, rocks and numerous other aspects of the game to give a real-world feel.
Sphax PureBDCraft x128 is a texture pack designed to make Minecraft look like a comic book. The pack makes the colors in nature and crafted items vivid, and the art for character models, mobs and blocks is stylized.
The oCd Texture Pack 1.8 is a texture pack inspired by the default pack. The pack keeps many of the same textures as the original pack, but makes all angles exactly 90 degrees and all spacing between blocks even.
Dokucraft: The Saga Continues [Official] [32x] 1.8.1 Dark/High/Light is the continuation of a previous texture pack that offers the players three variations: dark, high and light. Depending on which variation the player chooses, the game looks slightly different.
OzoCraft is a texture pack with a realistic and rustic feel, but it keeps the playfulness from the default texture pack. This pack is for a player who wants a more realistic Minecraft but wants to keep that simple, whimsical feeling.