First, I have some general suggestions about what I think makes for good maps.
1. No stand-alone towers/forts (archer camping grounds). If you want a high point where some archers would go to naturally, make it so that it is still pretty low to the ground, doesn't provide much cover, and it is still easily accessible for cavalry. The ruins maps with the old walls that have sunk into the ground are a great example of a balanced archer spot. Cavalry can run up the slope. Archer have to use the slope of the structure to get any cover from ranged attacks. But it's still safer than being on the ground.
2. Minimize high-wire trick locations for people to get to. I think it's pretty annoying when someone jumps around on some buildings or uses ladders to get on top of some skinny wall that wasn't meant for people, and the only way to get to them is taking the same long trek of jumping around, probably while being shot at by that person who went up there in the first place.
3. No "best" location, especially in the center of the map. Ideally, any particularly good spot to set up at should have a glaring weakness. If there's a fortification with great forward cover and is hard to access from the front (and thus easily defended), there should perhaps be another location to the flank of that location that exposes all the defenders (campers).
4. Any enclosed buildings should have multiple entrances that expose anyone who is camping a different entrance. So if there is a door on one side of a room and some guy is standing beside it with his sledgehammer raised and ready to attack anyone who enters, an archer should be able to go around to the other side and shoot in at him through a different entrance. That ice map that is all blue with just a castle in the middle is an example of a castle that is too easily camped.
5. Less is usually more. When you make choke points, people tend to stop at the choke point and defend it. If they go through it, it's like they are exposing themselves. Similarly, if there are good buildings, they stick to them. Narrow corridors bunch people together. But when it's rather wide open and any obstacles are pretty insignificant, you get a good sprawling battle (and it's less like a siege). So don't try to "direct traffic" so that players end up with really only 1 best path to take to maximize their safety. Make it more random, sparse, and unclear as to where to go. It's probably best that they decide where to go based on what they see happening on the battlefield rather than going where the battlefield terrain leads them.
Regarding specific suggestions for maps, I have one at the moment:
1. There's a map with a bunch of boats in the bay connected by docks, with the shoreline curving around the outside. The main battle happens on the boats/docks. I think that map would be better with the boats and everything moved closer to the midpoint of the shoreline. As it is now, the shore and the boats are like two very separate battlefields and you have to walk a very long dock to go between them. So each separate battlefield can't really be used to flank the other. But if the ships are pushed inland more, the shore becomes an extension of the battle on the boats and gives a worthwhile flanking option.