% is for Binary Values... I've always been curious why TGC didn't use 0b as they use 0x and 0c for the other formats., but they've always done odd things.

Anyway, as Bengismo says there's no real difference between putting say

ValueBin = %10101011 // Base 2

ValueHex = 0xAB // Base 16

ValueOct = 0x253 // Base 8

ValueDec = 171 // Base 10

Personally I find it useful to use the Number Base that reads the best for what I'm doing.

So... if I'm using Binary Flags, then I'll use % Binary Numbers... as then you can see exactly which Bits you're flagging

For Colours I tend to use Hex, as 0x00 to 0xFF (0 to 255) is a little easier to remember... especially as the 50% is 0x8

I've never used Oct ... not sure of a use case for it.

Then Decimal is just easier to do general Mathematics with.