1.13 we all know why.
1.9 for better combat (still sucks but better than 1.8)
1.7 for the landscape and new biomes
1.12 for the gorgeous colours.
1.11 for the hunger mechanic fix. I started minecraft with version 1.8.2 and I started snaphots with 1.9 a week or 3 before the first pre-release.