Now that the Creative inventory can be stored manually (not by numeric ID), I think it's time to reorder it.

• Building Blocks
  • Stairs & slabs next to their entire block
    • Or near them, for instance we can have 6 planks, then 6 wooden stairs and then 6 wooden slabs
  • Ore Blocks next to their Ores (except for Redstone Block)
  • Glass next to Stained Glass
  • Terracotta next to Stained Terracotta
  • Mossy Cobblestone / Smooth Stone / Smooth Sandstone / Smooth Red Sandstone / Smooth Quartz respectively next to their default block
  • Sandstones & Red Sandstones together
  • All Nether blocks together
  • Packed Ice next to Ice
  • Jack o' lantern & Melon Block next to Pumpkins

• Decoration Blocks
  • Nether Brick Fence next to the wooden ones
  • Glass Pane next to Stained Glass Panes
  • Double Flowers / Tall Grass next to Flowers / Grass
  • Move Slime Block to Redstone tab

• Redstone
  • Iron Trapdoor next to wooden ones
  • Weighted Pressure Plates next to the others
  • Stone Button next to wooden ones
  • Dropper next to Dispenser

• Transportation
  • Oak Boat next to the others
  • Empty Minecart next to the others

• Miscellaneous
  • Milk Bucket next to the other buckets
  • Iron Nugget next to Golden Nugget
  • All seeds together
  • Dyes sorting is inverted (white should be first)
  • Move Horse Armors to Transportation tab

• Brewing
  • Ingredients/brewing stand/cauldron should be put before all potions