I like #1, for sure! The second one looks a little dirty like it was dropped in the mud imo...but that's just my opinion! xD
Nice work. :3

Number one looks more plausible. I think the black spots are an issue with the second and against a darker base, some of the bright swirls look more artificial.

Still cool though .

I like the colors better in the first one. The second one is too dark in places to be a believable star which is a reactor for light and energy. Dark spots look kind of out of place because of that. I would even go as far as dodging in some white areas, maybe with a rendered cloud layer or something. Grae was spot on with the sharpness. You could benefit from a gaussian blur halo around the outside as well as a soft blur towards the edges. This will help it look dimensional too. You could also try to mess with the lens filter and bend the whole thing, or map to sphere before you overlay any of the swirls. That will keep your texture from looking like a cut out circle. Stars are tricky like that because you don't get to fake roundness with shadows, like for planets; you have to accomplish it with texture and perspective alone.

All in all though, I commend you for tackling something a little more complex like this. It's definitely a good direction to explore.

I like #1.

I like the first one. Much more dramatic.

I think the first one looks much more realistic.