First, PvP in Cyrodil is actually pretty good (excepting the lag, server issues, and class balance problems). I try to envision what a PvP scenario would be like in a game like Oblivion or Skyrim and I think it would look a lot like what ESO has implemented. In Oblivion and Skyrim, forts and keeps are pretty much just structures to frame quests around. In ESO, I was expecting to encounter dynamic tactics with keeps and fort that would set the imagination on fire.

For example, I was envisioning a bunch of archers able to get together on a wall and repel invaders with their arrow fire, instead you get a few people who do range, but when the wall breaks the defenders quickly scatter and resort to their own countermeasures. Organization and roles usually depend upon players being in a guild that has a plan or a play style. It can be very hard to find the type of group that you want to join in Cyrodil if you are a casual player (which I am not, but think of the possibilities that would open up if a casual player or PUG could enter Cyrodil and immediately find a group they are interested in joining or form their own group based around what they want to accomplish [i.e. gank, havoc, siege, scout, etc]), instead, you are frequently forced to follow the herd and it seems like conquering the map proceeds in a linear fashion for each faction. Then there is also the frustration of butting heads with other group leaders and trying to win over troops in your faction to your specific cause.

Here are some suggestions to the dev team to make Cyrodil a more interesting, dynamic, and adventerous place:

-Group tool in each faction that lets you see how many groups, how many players in each group and allows group leaders to give information on the group goals, and if it is a PUG or a Guild affiliated group
i.e. Keep Siege Group, PUG, 15 players, LFM or Gank Group, Guild: Death's Assassins, 5 players LF stealthy healer

-Incentive to organize players into semi-organized units i.e. if 10 sorcerers get together they would be able to use a giant group spell fireball that can take down walls and players (i.e. like a trebuchet, or ballista) as long as they stay in the same area and channel their powers together. Or perhaps if 10 archers line up on the wall together they can shoot farther and have a rapid fire volley ability as long as they stay together. Or if a bunch of templars with shields get together they can form a shield wall at the breach in a wall and in affect be a new wall that can block players from coming in for a certain duration or until their life runs out. Or if 5 nightblades come together at a focused part of the wall they can stealthily sap the wall and create a small hole in which maybe like 3 people every 10 mins can crawl through.

-Each Keep should have it's own Delve, an instance that players from any faction can enter and battle themselves and monsters oh idk like undead werewolves that are featured prominently in the CGI movies advertising the game. Keep the solo dungeons scattered throughout Cyrodil, but give rewards and other things for the faction that can dominate a dungeon or something.

Well, this is just the tip of the iceberg on Cyrodil improvements that I can think of. Devs contact me if you need input or suggestions.