I use realise because I'm British ^^
I use realize.
School has never told me this..... this is a mockery to everything I live for! Let schools rue they day they told me to only write the word as "realize" is it just me or does the letter 'Z' not really have any use except Zebra and perhaps a few other words? Zoo.....zone...... :l Zeus... wait no that's a name....
I tend to use the British English spelling because I'm used to spelling them that way.
"Realize" just looks better than "realise", really. And my computer tries to correct it to "realize" anyway. So why bother? Now, neighbour, colour, and behaviour are different, and I usually get in trouble for it.
We use British English in India. So, I have the habit of spelling it as "realise'".
In New Zealand we use the English spellings, so realise.
I spelled realised, and colour on a spelling test a while back, (It just seems to look better )and I got them wrong. This is because I live in America.
Realize, makes more sense to me cos' with the "s" it seems softer and less... I dunno it's hard to explain.
Then again I'd probably use both, since technically, they're both correct.
I prefer to use British English spellings to words. So realise. Even if it means I have to type it twice so the autocorrect doesn't correct it to American English spelling. XD