I like using markers because the colour is better and it's quicker to fill a shape than with a pencil. Also, there are some really nice coloured sharpies.
I like colored pencils. They are easier to blend, cheaper, and somewhat less permanent than markers. You can layer them all you want and they won't bleed through either.
I might just be really stupid but I'm so confused as to what markers are. I asked google but I keep seeing pictures of what to me looks like highlighters, sharpies and felt pens. Does markers encompass all those?
If it does then yeah I'll go for markers over coloured pencils because of how much fun it is to write with them. I never use coloured pencils, I always draw in black and grey.