In my opinion, burg rabenstein absolutely has to go. I feel like Hrafnin has a very long walk (all uphill) for attackers, leading to much downtime and potential defense-bias. It is one of the very few maps that would arguably be biased to the defense, at least in the usual low population. Ibdeles and Ridoma happen to be two of my favorite maps, since all maps that aren't broken tend to be among my favorites. That, and I see nothing wrong with either of them at all.
That one map where the defenders must (90% of the time, anyways) jump to their deaths from spawn definitely needs to go (and i say 90% since you can survive with only taking 1/2 - 2/3 damage if you are a pro). On that same map the attackers also spawn underwater, making their whole screen blue until they finally climb the really long staircase right in front of the flag. So if the 1 glitched spawn wasn't bad enough, to completely kill the map, that is. I have seen this one map empty a server when polls weren't enabled.
Other than adding new maps, I definitely think that fixing the bugs in the old ones would be a great way to get more players into siege. Plenty of maps have gates that can't be opened by defenders all the time, or they can only be opened from one side (still not sure if this is intentional or not... nothing like locking your whole defending team out of the flag building while it's getting capped). Not to mention that one map where defenders can't open the gate, but the attackers can... and open it from the outside too. That map wouldn't be too bad if it was bugged. While these fixes wouldn't necessarily draw in new players, it wouldn't give a reason for current siege players to up and leave prematurely.
As I mentioned earlier, many of the maps tend to be attacker-biased (even with no more overtime), especially with low population. With very high population (very very rare nowadays) the defending team has enough players to camp ladders almost endlessly, while in low-pop you are lucky if you can die and come back and not have to rush to the flag, then fight on the flag for the rest of the match. An interesting suggestion, and one that can't be fulfilled by the scene managers, unfortunately) would be to have variable spawn timers for defenders, with the variable being server population. This means when the server is at a relative high, or really just medium when compared to battle's standards, the respawn timer would be at 30 or so, as it always is now. But with lower pop, that time would decrease. If the server is a 4v4 (lowest possible to get multis) you can have 1 hero cut down the entire defending team, get to the flag, and cap it before they respawn. So sure, it might not draw more people to siege, but once again it will greatly improve it in its current state. And if it is a better game mode... perhaps more people will stick around.
And we already have working ballistaes. Thing is, they only work in conquest, which needs to be fixed first. I'll ask Ozin if they might actually work in the normal siege, but i doubt it.
@Apollo: Not quite sure what you are talking about. Those maps were only on siege between some patches (where they wrongly got in) and the hotfixes (where they got removed again). And right now they are definitely not in.
I personally hated ballistas in the conquest game mode... sure it was great that it helped the defenders (not that they ever needed help in that particular game mode) but the attackers could easily take them over and use them against the defenders. And with low population, you can't guard both the flag, the ladders, the gate, and the ballista. Heck, nowadays you really can only guard the ladders, or the flag, and hope they never get to the gatehouse. And if you split so that you've got half at flag, half a ladders, the ladder guys will get overwhelmed and die.. then the entire hoard of attackers will overwhelm the flag campers before the ladder guys even respawn, and boom.. attackers win yet again. While new gimmicky things such as this might draw a few curious people, I feel that it will innevitably hurt the game mode in the long run, once the curiosity dies down.
Also, believe it or not, open field maps pop up a lot... not sure if maybe one map is glitched or something, so you don't think its an open field but it is.. but they have been showing up for all time, and have yet to go anywhere. I played on one just yesterday or the day before. To be honest though (I know I am in the minority here) they change up the gameplay so much that I enjoy the open field maps. And they go by quickly (unless you've got a stacked defense team, which just means the entire round is a frantic flag-area-bloodbath.. which is epic fun) so they don't kill the servers too much. I don't even get mad losing a multi if I am on defense since it is such a refreshing time. Personally I like fighting in open fields, but I dislike battle due to the long wait time if you have got delayers and whatnot. And also open fields are much more fun when no one is expecting it so you have got at most 2 cav.