Ok, this question comes up a lot. Like, a lot. Truthfully, it's impossible to answer. There are a lot of things that go into a scent and more specifically a candle "filling your house". But, the question has been asked...so let's get into it.
Fill your house? What does that even mean?
First, what is your definition of "fill your house"? How sensitive is your sense of smell? Some people can smell something from miles away while others fail to miss the week-old tuna in their fridge. Maybe it's a silly question, but it is important to be realistic about this sort of thing when considering what scent and candle size combination to put in your home.
How big is your house?
How big is your house? It's not often thought about, but a large home is going to be way harder to fill than a smaller home. Two story homes are always going to be difficult to fill simply due to their size. Smaller, rancher style homes might be easy to fill, but also, too easy to fill. One second your candle might smell great, but the next second you can't stop smelling your cat's freshly used litter box. There are pro's and con's to each but don't worry, there are ways to combat all of these things!
What scent are you looking at? Some scents are just naturally stronger than others. Scents such as vanilla and cotton are going to be much softer than scents such as pumpkin or oakmoss.
What size candle are you looking at? Yes, each candle size is going to throw the scent differently. Large candles, by nature of their jars and scent to wax ratio are going to "throw" or allow more scent into the air than a smaller jar would.
See where this is going?
So, now that you are aware of all the factors that go into this crazy question, what WILL fill your house best? Do you have a small home with a sensitive sense of smell? A small candle will be more than enough to fill your home. Is your home on the larger side and your nose not up to par? You may need two or three candles to sufficiently "fill" your home. Again, this is all perspective, so please, consider all the options and give it a try for yourself.