Hmm. I'll give a general overview, a bit about what I like/dislike about each, and then a suggestion or two.
General overview: I filled the rest of this in first, and forgot what I was going to up the top here. <<
My favourites would have to be B], for the eyecatching, and H], in terms of actual info, and layout with that info.
A]
This one is cute. The colours/composition work well, and it give the important info, such as the name, rates, and even what game it is (which would attract me if I was seeing it on a non-RO related site).
Only problem is, it doesn't tell/show me what makes heRO different/special/stand out.
B]
Certainly grabs my eye. Of all the pictures/compositions, this is probably my favourite. It looks more professional.
However, it relies on the viewer being able to recognise the game from the viewer. This alienates anyone who hasn't played before, but may be interested, if they knew what game it was. It also doesn't say what makes heRO special.
I think it is also a little top heavy. Perhaps crop a bit more of the bottom off, and use that new space to extend the sky, and put in "Ragnarok Online"?
C]
The most informative of them all. Tells me the server name, rates, what game it is, and a bunch of the features.
The picture is cute, but is dominated over my the large amount of white space. It doesn't catch the eye the way the top two do.
D]
Simple and cute. Server name, rates, and shows some of the custom headgears. Would be nice with a border or some such to contain the white space, on a RO related site.
However, doesn't really tell any of the server features again. There's a lot of private servers out there. You want to entice people to choose your's over all the others. Sellsellsell.
E]
Like the idea, however, same as the above one, I think.
F]
Same as above again. However, I prefer E] over this one, simply due to the empty space in the top right of this one. It stands out, whereas, in E], it is filled in nicely.
G]
A little cliche. A lot of the free-to-play games out there currently are light vs dark, and focus on that a lot when advertising. heRO is so much more than that, and should sell that point more than just light vs dark.
H]
Don't mind this one too much, either. Gives the basic info. Shows customs. Lists other customs.
I don't think any of them sell the server properly. Some do in one area, some in another. I think the best bet, if it is supported on the place you are looking at using these on, is to go animated (or to find a picture with wonderful composition, and not to be afraid to layer text over it in some parts). Use one with a picture and a title to catch the eye, and once you have caught it, flash to a new image, listing some of the custom/special things about heRO. Maybe include a cropped screenie or two. But keeping it simple. Too many flashy images hurt the eyes. XD
The only problem here would be to make sure it animates at a nice speed. Time for reading, but not too long.
Something with te general flow of images like the one in your sig more if good, but perhaps include one of the drawn images for original eye-catching, and, if the site is not RO-related, focus more on the custom features and general look of the game, rather than server stability, etc.
But yeah. A lot of it depends on WHERE you plan to use the banner. What type of people are your target audience?