Server stability (and specifically its ability to handle capspam/furrballs) dropped markedly with the re-institution of POBs.
The reason for this is the fact that POBs, unlike static bases and planets, constantly run fairly complicated script - consuming resources, generating shields and powering/aiming weapon platforms, allowing and disallowing player docking, maintaining and calculating limited items/commodities, among other things.
This adds to the script-load while also being layered onto a very old vanilla script, which is admittedly antiquated at its root.
Long way of saying; Pretty much all of them.
Players may have individual qualms about individual bases - some will rage against, and some will defend every base mentioned here.
I prefer a larger blanket - one not based on any sense of loyalty or factionhate.