That's actually a really tough question.Venezuela is the 3rd largest pasta consumer in the world, and yet rice is a staple.Not to mention bread - people will buy a whole "canilla" (which is a short baguette) and just put a slab of cheese in it.
I think I'd have to go with pasta first. It's quick to make, I've always got some form of pasta sauce in the fridge, and if not, it'll be an aglio e olio, or a traditional Alfredo (butter and parmesan cheese)
Rice is second. Classic accompaniment to Venezuelan food and essential for Indian food.
Then come bread. A cheese sandwich is my favourite, and probably most common breakfast - at around 10.30 am
Love potatoes, but they need lots of time to cook, so they'll come in 4th.
Finally, lentils, beans, grains.