Which would be the largest or which would be the smallest if they were positioned on their own in empty space?

yea that's right, your premises are right anyway, your conclusion doesn't necessarily follow from it.. but yea, big and small are relative measurements, and they're the same thing when there's no matter.. there's a theory that's sort of popular among cosmologists that maybe neither the big bang nor the oscillating universe theories correctly describe how things go and how it actually happens is like this, the universe is born, it expands to as big as it can become while matter comes into existence, eventually all the matter decays away to nothing, then with no frame of reference the universe isn't 'big' any more, it's nothing at all because there's nothing in it, and when it's in that stage of its life it starts the expansion again from this point, keeps becoming bigger but at the same time it oscillates between big and small

Well, 'the sun' is only a medium sized star, and we've split the atom, so neither really.

The facts regarding the 'big bang' aren't necessarily mutually exclusive from belief in a 'creator', but inferring the existence of an exponentially more complex creator (who did not require creation itself) in order to attempt to explain the existence and apparent complexity of the universe is redundant (at best).

There is also nothing saying that the 'big bang' was the beginning of 'everything', just our current space/time continuum.

Size is only relevant when compared against something else. For instance, if our Sun was alone in empty space, it couldn't be described as small or large. But if an atom is placed alongside it, then we could regard it as large. But, then, if a Galaxy was placed in the same area, we would regard our sun as small and the atom as minuscule.

There is a good site called something like "Star size comparisons" which puts sizes into perspective and is amazing.

Much of man's perceptions are rooted in relativity. Nothing relative is actual. If it were actual it would be independently true. Many spend their entire life trying to escape independent TRUTH by which all the fragments exist because it is something they cannot control. Basically THE TRUTH simply proves that they are fools and man doesn't mind his foolishness he just wants everyone else to say it is true for the ego plays king of the hill and in its attempt to rise to godhood it must use pretense. All humans subconsciously seek Godhood as if we instinctively know we once enjoyed it before the self existed yet at the same time the self and what if finds its identity in is to high a price to pay therefore it seeks to out do all of its competition as it wants it cake and eat it too.

Philosophy section?

Anyway..

Relative: You first need something as a unit of comparison. From that you can compare size.

Whichever you look at first, if it's a big thing then the other will be smaller, If small then other would be bigger.

well, you started off with a reasonable philosophical question and then went totally non-sequiteur

if i can re-phrase your question :

Because A, therefore π

That makes no sense at all.