Which is the biggest star other than the sun?

It’s likely most stars are larger in mass than the Sun. Visually, per perspective, the Sun is the largest.

However, if you count literally all stars, then our sun is twice the average mass. But these additional stars I’m adding in are remnant cores. So choose your definition. Of the “normal” shining stars, the Sun is average or little; of all “literal” stars, the sun is a bit big.

However once more, if you are trying to find the largest in mass, good luck – it’s pure speculation. But largest by volume, then you have a chance. UY Scuti and VX Sagitarius are the largest stars by apparent volume. But we really can’t know for sure. These are constantly updated by observations and data re-analysis. What does help is that luminosity is an indication of mass, but the physical dynamics of this indication are only theoretical.

More so, consider that we can’t see all the stars out there; but the ones we can are likely really big, and those small are hard to see. This question ends up being philosophical, semantic, and humanistic more so than cosmological. So maybe the sun is “biggest” since it looks big compared to all others.