Ever since Beta 1.8, the world generation has been fairly flat and homogeneous. Release 1.7 alleviated some of the issues with the terrain, but it's still honestly kind of boring. Then suddenly, 1.8 came along and gave us world customization options. Many customized world presets have tried to fix the boring terrain, but I think you'll come to the conclusion that this one stands out:

{"coordinateScale":684.412,"heightScale":888.176,"lowerLimitScale":423.45068,"upperLimitScale":388.2465,"depthNoiseScaleX":409.24646,"depthNoiseScaleZ":409.24646,"depthNoiseScaleExponent":0.8546479,"mainNoiseScaleX":80.0,"mainNoiseScaleY":160.0,"mainNoiseScaleZ":80.0,"baseSize":8.5,"stretchY":12.0,"biomeDepthWeight":0.5,"biomeDepthOffset":0.0,"biomeScaleWeight":2.0704226,"biomeScaleOffset":0.0,"seaLevel":65,"useCaves":true,"useDungeons":true,"dungeonChance":17,"useStrongholds":true,"useVillages":true,"useMineShafts":true,"useTemples":true,"useMonuments":true,"useMansions":true,"useRavines":true,"useWaterLakes":true,"waterLakeChance":4,"useLavaLakes":true,"lavaLakeChance":80,"useLavaOceans":false,"fixedBiome":-1,"biomeSize":4,"riverSize":5,"dirtSize":33,"dirtCount":10,"dirtMinHeight":0,"dirtMaxHeight":256,"gravelSize":33,"gravelCount":8,"gravelMinHeight":0,"gravelMaxHeight":256,"graniteSize":33,"graniteCount":10,"graniteMinHeight":0,"graniteMaxHeight":80,"dioriteSize":33,"dioriteCount":10,"dioriteMinHeight":0,"dioriteMaxHeight":80,"andesiteSize":33,"andesiteCount":10,"andesiteMinHeight":0,"andesiteMaxHeight":80,"coalSize":17,"coalCount":20,"coalMinHeight":0,"coalMaxHeight":128,"ironSize":9,"ironCount":20,"ironMinHeight":0,"ironMaxHeight":64,"goldSize":9,"goldCount":2,"goldMinHeight":0,"goldMaxHeight":32,"redstoneSize":8,"redstoneCount":8,"redstoneMinHeight":0,"redstoneMaxHeight":16,"diamondSize":8,"diamondCount":1,"diamondMinHeight":0,"diamondMaxHeight":16,"lapisSize":7,"lapisCount":1,"lapisCenterHeight":16,"lapisSpread":16} 

The preset above is the result of several hours worth of fine-tuning, so I hope you thoroughly enjoy it.

This preset features:

• Large lakes (7.8/10 too much water)

• Extreme Hills that actually live up to their name

• More height variation within biomes

• More dungeons (and I still can't seem to find any, even with Spectator mode)

• A sense of nostalgic atmosphere

If you still aren't convinced, check out these screenshots