Some ideas and improvements I would like to see...in no particular order...
1. An end to the lag. I would love to see many more players enjoying PVP (all that the same time).
2. Expansion of the Cyrodil map. Perhaps neighbouring regions could be added to spice it up. There seems to be more imperial lands to the South East and South West of the map (Niben River Valley and Kvatch areas).
3. Add another faction! Its time the Imperials martialed their forces and tried to restore order.
4. Include the Imperial City itself in the normal campain map. Let the Hammer spawn there.
5. Improve the rewards. Perhaps bring back the master's weapons or similar as end of campaign rewards for the top scoring players.
6. Give guilds a big incenitve to hold keeps other than just a guild store. Holding a keep should enrich a guild directly in some way, perhaps extra gold, a corresponding additonal guild store in the respective alliance capital tied to who holds the keep, and/or an AP multiplier for its members in cyro. This will encourage more cooperative play and bring the merchant guilds into Cyrodil.
7. Night capping/morning capping is problem, which ruins the competitive nature of pvp. In the EU campaign I play on, one side often logs in en masse in the early hours, takes over the whole map taking all the scrolls. When the other alliances log in, the morning cappers have the emp bonus, and all the scroll bonuses as well giving them a massive combat advantage. The bonus for holding an enemy scroll should be on a timer, so if one alliance is dominating, the effect of holding the enemy scrolls should eventually fade, levelling the playing field. The increase in campaign points each tick should increase when the buffs fade away, so there is still an incentive to hold the enemy scrolls, but the combat advantage is gone. Too much morning capping and the unlevel playing field leads to an empty Cyrodil as one side logs off in frustration, and that sucks for all pvp players.
8. Bunny hopping...looks stupid, but its mitigating AOE damage, making a player harder to target, and minimises CC effects, there should be a stamina cost to do it in combat, just like there is for roll dodge or blocking.
9. For the love of god....please make streak blockable or increase the cost of this skill much more...it does too many things.
10. Animation cancelling. Mixed views on this, but it strikes me that a defending player should always be able to counter the attacking player's attack, to do this, they must see it coming.
11. Combat Bug...enough already.....make it go away! Let people mount their horse in combat, at the very least.
12. Naval combat...(a friend's idea, but I liked it).