I believe that there are two 'levels' of issues in PvP, the first being existing bugs which are covered by a number of other threads, and the second being what I perceive as a failure of game design which I wish to discuss here.
It seems to me (in EU) that the current set up is a failure, competition is killed off by players and campaigns used as 'buff' providers. E.g. AD have had an emperor on Haderus for nearly two weeks. The campaign needs to be put out of its misery. I think Chillrend in EU is DC controlled and Thornblade is AD controlled (again, I think). Only Azura's Star actually has PvP.
I think that there are three major culprits in this: 1) human nature, i.e. players following the easiest path to success. 2) Over and under populations. 3) Night capping de-motivating peak-time players.
I am keen to hear what could be done to address these issues and also if people think that there are additional failures of game design that need addressing (not bugs although these too need addressing e.g. 8/10 players crashing during a siege and the attackers taking the now undefended keep).
To address 1) ZOS need to incentivise competitive PvP play with buffs and alliance points. Human nature will always take the easiest path and therefore the easiest path needs to be good, competitive PvP. More alliance points need to be given for alliance objectives (taking/defending keeps and scrolls). I hope that this would encourage players to fight harder at objectives rather than farm AP points at suicide spots or by camping a resource tower.
2) when there is a significant population difference, the low population alliance(s) needs to be buffed exponentially to be competitive, as an extreme example when one alliance is locked and the other two are on one bar, direct hits from siege engines could be fatal. Hopefully this would draw in players to imbalanced campaigns, hopefully returning the campaign population to a better balance.
3) it is demoralising and frustrating that evenly matched alliances can make hard fought gains during high population times that are completely undone during low population time. Linking back in with 1) these low-pop players don't seem to choose different alliances to compete with each other as it is easier to faceroll PvDoor as a same alliance group.
My solution, although this is partially diagnostic in order to ascertain if night capping really makes that big a deal, would be to double the number of campaigns but time lock these campaigns. E.g. Haderus would become Haderus AM and Haderus PM. If you generally play between Midday and Midnight, home on the PM campaign and at Midnight the campaign "saves" and closes with players being moved to Haderus AM which opens from Midnight to Midday.
You are automatically a guest of your sister campaign and AP gains count for your home campaign score so you can start earlier or finish later if you wish too with no penalty to your score or chance of becoming Emperor. This, I hope, would create more of a campaign ownership for regular PvPers as they have more of an influence over their chosen campaign and are not forced to concede victory or accept defeat because they cannot play 24 hrs a day.