Elo and good to have ya back to the studio. The tag that catches my eye the most is the last one, the effects in it are just eyecatching. A lot of the work of yours I have seen is concentrated about the skies,with planets and the heavens etc. which is good. Here are my ratings...
In the first sig I just don't think the render fits the sig, some of the effects on it just don't make it compliment the character inserted. It's very busy on one side compared to the other and you should try and even it out, if you did take the character out it wouldn't look right so it's a win/losse sorta situation. The text is great, just blends in with the rest of the tag.
The second one has far too much blank space, I'm not a fan of blank spaces on sigs, especially when white so I suggest filling it with something. I like the font you've used on there too. Pretty much the same with the third tag, although there is a lot less white space on it.
Fourth tag is really good, the it flows and it blends. One thing I would suggest is adding some text in the same font you've used for the second and third tags, just to give it the complete look, I also suggest adding a 1px border. [If there already isn't one, it's harder to see on this skin].
I've already commented on the last one but i'll reiterate... my favourite because of the use of effects and the fact you've made that kind of border work well with the signature, which is hard. Overall i'd give you a 3.5/4 out of five and 4.5/5 for the last one. Well done, keep up the good work and good luck in the future.